Media playback is unsupported on your device Media caption Gen Abdel Fattah Younes was an ally of Col Gaddafi for many years 
 
 The military commander of the Libyan rebels fighting to topple Col Muammar Gaddafi has been killed, the rebel National Transitional Council says. 
 
 NTC head Mustafa Abdul-Jalil said Gen Abdel Fattah Younes was killed by assailants, and the head of the group responsible had been arrested. 
 
 He said Gen Younes was summoned for questioning about military operations, but never made it to the meeting. 
 
 Reports said Gen Younes was suspected of ties to pro-Gaddafi forces. 
 
 "With all sadness, I inform you of the passing of Abdel Fattah Younes, the commander-in-chief of our rebel forces," Mr Jalil announced late on Thursday. "The person who carried out the assassination was captured." 
 
 Analysis There are a lot of questions about exactly what happened on Thursday and what the sequence of events was. We're told that Gen Younes had been due to appear before a panel of rebel judges to answer a number of questions on a military matter. We're not entirely sure what that was. In a conflict like this where there are not many facts and one side of the country is fighting another, we tend to get an awful lot of rumours and suggestions. For what it's worth, some of the ones we're hearing is that there was a worry among the rebels that the military campaign was not going very well. They wanted to question the general. Some of the speculation we're hearing in Tripoli, coming from Col Gaddafi's side, is that the general was simply not trusted by the rebels. 
 
 Mr Jalil did not elaborate on the identity or motivations of the assailants. It is not clear where the attack took place. 
 
 Correspondents say Mr Younes was not trusted by all the rebels because of his previous role in cracking down on dissidents. 
 
 Two aides to Gen Younes, Col Muhammad Khamis and Nasir al-Madhkur, were also killed in the attack, Mr Jalil said, adding that none of the bodies had been recovered. 
 
 There will be three days of mourning in their honour, he said. 
 
 Gen Younes is a former Libyan interior minister who defected to the rebel side in February. 
 
 He was also part of the group that helped bring Col Gaddafi to power in 1969. 
 
 Some unconfirmed reports said Gen Younes and two aides had been arrested earlier on Thursday near Libya's eastern front. 
 
 Shortly after the announcement of Gen Younes' death, gunmen entered the grounds of the hotel in the eastern city of Benghazi where Mr Jalil was speaking, reportedly firing into the air before being convinced to leave. 
 
 UN divisions 
 
 Earlier on Thursday, rebels said they had seized the strategically important town of Ghazaya near the Tunisian border, after heavy fighting with Col Gaddafi's forces. 
 
 They reportedly took control of several other towns or villages in the area. 
 
 The rebels are struggling to break a military deadlock five months into the uprising against Col Gaddafi's rule. 
 
 Abdel Fattah Younes Helped Libyan leader Col Muammar Gaddafi take power in the 1969 coup that ousted King Idris 
 
 Close advisor to the Libyan leader for four decades, rising to the post of general and training Col Gaddafi's special forces 
 
 Appointed interior minister 
 
 Quit the government on 22 February 2011 and defected to the rebels - one of the earliest such moves by a senior official 
 
 Appointed as the opposition's military chief in April, but faced mistrust due to his past ties to Col Gaddafi 
 
 Rebels control most of eastern Libya from their base in Benghazi and the western port city of Misrata, while Col Gaddafi retains much of the west, including the capital, Tripoli. 
 
 Late on Thursday AFP news agency reported explosions shaking the centre of Tripoli, as state TV reported that planes were flying over the Libyan capital. 
 
 Nato, acting under a UN mandate authorising military action for the protection of civilians, has carried out regular airstrikes in the Tripoli area. 
 
 Meanwhile, the South African ambassador to the UN, Baso Sangqu, warned that supporters of the rebels were in danger of violating UN sanctions. 
 
 His comments came a day after Britain granted the rebels diplomatic recognition and said it would unblock £91 million ($149m) in frozen Libyan oil assets for the rebels. 
 
 "We have noted the calls for Gaddafi must go," Mr Sangqu said. "We maintain that such statements do not bring us any closer to a political solution." 
 
 The BBC's Barbara Plett reports from the UN that the growing trend to grant diplomatic recognition to the Libyan rebels is facing opposition on the Security Council, and that moves to back the rebels will further polarise Council members. 
 
 Portugal has become the latest of about 30 countries to have recognised the NTC. 

 The death of rebel military commander Abdel Fatah Younes has thrown a wrench into efforts to organise the makeshift opposition army and risks putting Benghazi, and perhaps the wider effort to oust Gaddafi, into disarray. Younes was the subject of much scrutiny and scepticism among anti-regime Libyans both in the country and abroad since he became the highest-profile government figure to defect to their side, on February 20, after five days of increasingly bloody protests in Benghazi and elsewhere in the country. Jalil's remarks Read a transcript of the Libyan rebel leader's statement on the death of Abdel Fatah Younes. Though the opposition National Transitional Council quickly made Younes chief of staff of the ragtag rebel armed forces, a power struggle ensued between Younes and longtime exile Khalifa Hifter, a former general in Muammar Gaddafi's army. For much of March and April, control of the rebel army seemed to pass back and forth from Younes to Hifter. Sometimes it seemed neither was in control. In recent months, the dispute seemed to resolve. The NTC presented a more disciplined public face to the media, eliminated contradictory remarks about who was in charge and minimised Hifter's role in favour of Younes. It replaced Defence Minister Omar Hariri with Jalal al-Dogheily, a senior opposition figure who was older than both Younes and Hifter and whose job was to both coordinate military affairs and mediate between the two men. 
 
 
 
 Very little was said about Younes since then - a good sign for the NTC. But that came to an end on Thursday. Looming questions Mustafa Abdul Jalil, the chief of the NTC, blamed Younes's killing on gunmen in a press conference late on Thursday night. He said Younes had been summoned from the front line to appear for questioning before a judicial committee investigating "military affairs," but that he and two aides - a colonel and a major - were killed before he could appear. The head of the "armed group" that killed the men was arrested, but the bodies of the men had not been found, he said. 
 
 
 
 Sources close to the NTC told Al Jazeera earlier on Thursday that Younes had been arrested and was suspected of engaging in unauthorised communication with Gaddafi's representatives and had possibly even helped supply regime troops with weapons - a dire offence against the rebel cause, but one that could not be immediately proved. Jalil did not directly blame Gaddafi's forces for the killing, but he said the longtime leader continued to try to sow discord in the rebel ranks. 
 
 
 
 Younes's death, while possibly under investigation, throws open a power vacuum in the rebel hierarchy. Many Libyans fear such a void will spawn more violence as others move to fill his role as military commander, while his allies seek retribution. Possible scenarios Several theories about Younes’s death were circulating among the Libyan community and observers on Thursday night. 
 
 
 
 Gaddafi had placed a multi-million dollar bounty on Younes's head after his defection, which could have been reason alone for the assassination. 
 
 
 
 Then there was the possibility that he had been involved in a confrontation with rebel officials after being recalled from the front lines by the NTC for investigation. Some believed he had been shot after tensions flared at a meeting between the two sides, though Jalil's claim that Younes had been killed after being released from an interrogation seemed to belie that. 
 
 
 
 Finally, some believed, it was possible that Younes had been targeted for assassination by a rival, perhaps even Hifter. There was no proof to support the accusation, but it reflected a fear among Libyans in the opposition that political machinations had gotten dangerously out of control. 
 
 
 
 Younes’s home was under heavy armed guard on Thursday evening, and some Libyan activists expressed fear that his tribe, the Obeidat, would seek retribution for his killing. 
 
 
 
 Gaddafi relations 
 
 
 
 Younes had been close to Muammar Gaddafi since the bloodless 1969 coup that brought the Libyan leader to power. He had attained the rank of general and served for years as Gaddafi’s trusted interior minister. 
 
 
 
 Younes also controlled a brigade of special forces troops garrisoned outside Benghazi, long known to harbour anti-Gaddafi sentiments. When he announced his defection and entered the city with his men, it swung the battle decisively in favour of the opposition and drove Gaddafi’s forces out of Benghazi, which has served as the de facto rebel capital ever since. 
 
 
 
 Yet even that pivotal victory cast a shadow. Many Benghazi residents have said that Younes, perhaps as part of a negotiation to end the fighting, allowed regime troops to escape the city. Those who escaped may have included Abdullah al-Senussi, Gaddafi’s intelligence chief, who had been dispatched to Benghazi to put down the demonstrations and was recently indicted by the International Criminal Court for organising the killing of protesters. 
 
 
 
 Younes-Hifter rivalry? 
 
 
 
 Younes was never enthusiastically embraced by Libyans in the east, and that made him vulnerable to a challenge. 
 
 
 
 Hifter, despite having left for exile in 1987, was warmly welcomed when he returned in March. 
 
 
 
 Hifter had led troops during Libya's war with Chad in the 1980s, after which he switched sides to join the long-simmering anti-Gaddafi movement. Hifter settled in the United States, in Virginia, five miles from the headquarters of the Central Intelligence Agency. For roughly two decades, he was involved in coordinating the Libyan opposition in exile. 
 
 
 
 Hifter’s return to east Libya was greeted happily by rebels who felt he could bring leadership to opposition forces mired in the desert west of Benghazi. 
 
 
 
 Video clips posted to opposition Facebook and YouTube pages showed Hifter touring the front lines, much as Younes had after his appointment, looking very much the general. Click here for more of Al Jazeera's special coverage 
 
 Hifter briefly appeared to replace Younes as the commander of the rebel forces. In late March, a spokesman for the rebel military announced as much in a press conference. 
 
 
 
 In late April, El-Siddik Hifter, the general's son, told Al Jazeera that his father was responsible for commanding rebel troops in the field, while Younes served as chief of staff back at headquarters. Omar Hariri, defence minister at the time, represented the military before the NTC, he said. 
 
 
 
 El-Siddik, who had returned to Benghazi to serve as an aide to his father, said the three men worked together as a kind of military council and made decisions collectively. Mustafa Abdul Jalil, the chairman of the NTC - and the man who sources said issued a warrant for Younes’s arrest on Thursday - was a figurehead and commander in chief only in name, Hifter said. 
 
 
 
 Despite his son's words, Hifter seemed to become marginalised. After weeks of murky struggle between Hifter and Jalil, the NTC quickly found itself backtracking. 
 
 
 
 Abdulhafiz Ghoga, the NTC's vice chairman and spokesman, told Al Jazeera in an interview a week later that Younes was at the top of the army’s chain of command. 
 
 
 
 Hariri represented the military before the NTC, it was true, but Hifter was only a commander, one of many leaders of the newly formed rebel brigades, he said. 
 
 
 
 Jalil, he said, had ultimate power as commander in chief. While day-to-day military decisions were left to commanders in the field, Jalil would have final say. 
 
 
 
 Murder mystery 
 
 
 
 Much remains to be learned of Younes's murder. According to Jalil, he was ambushed en route to a meeting with NTC representatives. Whether they were seeking to discuss military issues or to investigate Younes’s alleged collaboration remains unclear. Also unclear is where Younes’s body has gone - Jalil said it has not been recovered. While Jalil blamed Gaddafi loyalists for the attack, Tarik Yousef, a professor at Georgetown University who lived in Benghazi, said he discounted the idea that regime gunmen could have killed Younes, given the commander’s constant security. "I think it's a wake-up call for the National Transitional Council to deal with the matter of security within the cities under its control," he told Al Jazeera. The military structure, he said, is "highly undisciplined and not subject to the typical norms of command and control". Younes's death is "a very unpleasant development at a critical moment," he said. Follow Evan Hill on Twitter: @evanchill
– The Libyan rebels’ military chief along with two of his top aides were shot and killed today, reports the BB. Rebels blamed Gadhafi loyalists and said they had made an arrest, but the circumstances surrounding the assassination of Abdel Fattah Younes remain murky. Younes had served as Gadhafi’s interior minister before defecting to the rebels, but he had reportedly been summoned from the front lines for questioning that he still maintained ties to the Gadhafi regime. He got shot before that questioning occurred. Younes also had been embroiled in a power struggle with another Libyan commander. However the investigation shakes out, one thing is clear, writes Evan Hill of al-Jazeera: The killing "has brought a screeching halt to efforts to organize the makeshift opposition army and risks throwing Benghazi, perhaps the wider effort to oust Gadhafi, into disarray."