Pakistani Prime Minister Shaukat Aziz has promised a judicial enquiry into the killing of a local journalist.
Hayatullah Khan had been missing for six months
The body of Hayatullah Khan, 30, who reported the death of an alleged al-Qaeda commander, was found near Mir Ali in North Waziristan tribal region.
Mr Aziz's pledge came amid protests demanding the arrest of the killers.
Mr Khan disappeared in December after reporting that Abu Hamza Rabia had been killed by a US missile - not in a bomb making accident as claimed by Pakistan.
Speaking at a conference Mr Aziz said, "We will constitute a judicial inquiry into the murder of journalist Hayatullah Khan... Such incident was immensely unfortunate and disturbing."
Hundreds of tribesmen, including journalists, protested in Khar, the main town in Bajaur, demanding arrests over the killing - as well as protection for journalists working in the tribal region.
"The government has failed to find the real culprits in Khan's abduction and killing," an opposition legislator Maulana Mohammad Sadiq told the Associated Press news agency.
On Saturday, journalists and opposition lawmakers walked out of the National Assembly in the capital, Islamabad, to protest against Mr Khan's killing.
Journalists have pressed demands for an inquiry
Relatives found Mr Khan's body 3km south of Mir Ali near the Afghan border on Friday.
He had been handcuffed and appeared to have been shot from behind while trying to escape, his brother, Ehsanullah, told the BBC.
The journalist had lost a lot of weight and had grown a long beard.
Mr Khan's brother said the handcuffs were of a type usually used by security forces.
The BBC's Haroon Rashid in Peshawar says it is a mystery who kidnapped and killed Mr Khan.
Both the militants and the authorities denied knowledge of his whereabouts during the six months he was missing.
Local tribal journalists' organisations have blamed the government for his death because it failed to rescue him.
Mr Khan was seized by unidentified gunmen on 5 December.
Days earlier, the Pakistani authorities had said an al-Qaeda commander they named as Abu Hamza Rabia had been killed with four others in a blast at an alleged militant hideout in North Waziristan.
The official version was that bomb-making materials had exploded by accident.
But locals said the men were killed by a missile fired from an unmanned US drone.
Mr Khan took photographs of what appeared to be pieces of a US missile at the scene.
Pakistan is a close ally of the US in its "war on terror" but reports of US strikes on Pakistani soil provoke anger among opponents of the government in Islamabad.
Hayatullah Khan worked for a Pakistani English-language newspaper and a foreign photo agency.
The New York-based Committee to Protect Journalists said he had in the past been threatened by security forces, suspected Taleban members and tribesmen for his reporting.