Libya conflict: Nato summit fails to secure new planes
A Nato meeting of foreign ministers on Libya has ended without a commitment from allies to send more strike planes.
Neither the US nor Italy have indicated they will respond to calls to join ground attacks.
Nato Secretary General Anders Fogh Rasmussen said the threat to Libyan civilians would not disappear while Col Muammar Gaddafi was still in power.
Reports suggest pro-Gaddafi forces have been using cluster bombs against the rebel-held city of Misrata.
New York-based Human Rights Watch said its officials had seen the internationally banned munitions - which are dangerous to civilians because they scatter small bomblets over a wide area - fired in residential areas of the western city.
A Libyan government spokesman denied the reports.
Nato pilots are enforcing the current UN resolution to establish a no-fly zone and to protect civilians in Libya, which has effectively been split between forces for and against Col Gaddafi since a revolt against his rule began in mid-February.
The current UN resolution makes no mention of regime change, but an open letter by the US, UK and French leaders on Friday said there could be no peace while Col Gaddafi was in power.
At the Berlin conference, Mr Fogh Rasmussen said there were indications that allies would provide extra strike aircraft needed for the operation in Libya.
"We have got indications that nations will deliver what is needed... I'm hopeful that we will get the necessary assets in the very near future," he said.
But although US President Barack Obama said the US and Nato had averted "wholesale slaughter" with their campaign, he added that despite a military stalemate in Libya, there was no need for greater US participation in enforcing the UN-mandated no-fly zone.
Italy - which is thought to have been identified as a key potential contributor - also seemed to rule out ordering its aircraft to open fire.
Rome has made air bases available for Nato forces, but the eight aircraft it has supplied to the effort are only being used for reconnaissance and monitoring.
"The current line being followed by Italy is the right one and we are not thinking about changing our contribution to the military operations in Libya," Reuters reported Italian Defence Minister Ignazio La Russa as telling reporters in Rome.
Meanwhile, Russian Foreign Minister Sergei Lavrov suggested Nato was exceeding its UN mandate, and called for an immediate shift in its policy.
"We believe it is important to urgently transfer things into the political course and proceed with a political and diplomatic settlement," he told a Berlin press conference.
Only a few of Nato's 28 members - including France, the UK, Canada, Belgium, Norway and Denmark - are conducting air strikes.
In their open letter published earlier on Friday, Barack Obama, David Cameron and Nicolas Sarkozy said Nato must maintain military operations to protect civilians and maintain pressure on Col Gaddafi.
To allow him to remain in power would "betray" the Libyan people, they wrote.
In an interview later with Associated Press, the US president said Col Gaddafi was "getting squeezed in all different kinds of ways", and was running out of money and supplies.
But French Defence Minister Gerard Longuet suggested a new UN Security Council resolution would be needed for Nato allies to achieve their goals in Libya.
Speaking on French radio, Mr Longuet conceded that ousting Col Gaddafi would be "certainly" beyond the scope of the existing UN Security Council Resolution 1973 on Libya, and could require a new council vote.
"Beyond resolution 1973, certainly it didn't mention the future of Gaddafi but I think that three major countries saying the same thing is important to the United Nations and perhaps one day the Security Council will adopt a resolution."
Rebels holding out
While politicians debated the way forward, fighting on the ground and Nato bombing missions have continued.
Libyan state TV reported Nato air strikes had hit the cities of Sirte - Col Gaddafi's birthplace - and Aziziya, south of the capital Tripoli.
There were also reports of rocket strikes by pro-Gaddafi forces on the western rebel-held city of Misrata, as well as cluster bomb attacks on the city.
Steve Goose, HRW's arms division director, said it was appalling that Libya was using the munitions in residential areas.
The bombs, which have been banned under the terms of an international convention since last August, generally leave large numbers of unexploded submunitions on the ground, where they continue to pose a risk to civilians, especially children.
HRW researchers said they had retrieved fragments of a Spanish-made 120mm-mortar projectile, which opens in mid-air and releases releases 21 submunitions over a wide area.
Spanish officials have yet to comment on these reports. Spain ratified the convention against cluster munitions two years ago, but the fragments found in Misrata were apparently produced in 2007.
Rebels in Misrata have been holding out against attacks for two months, but UK Foreign Secretary William Hague stressed that Nato needed to act swiftly to prevent a "massacre" in the city.
He said Nato had been constrained by the need to avoid civilian casualties but had probably prevented the city from being overrun by Col Gaddafi's forces.
The BBC's Orla Guerin in Misrata said staff at a hospital there were battling to treat civilians injured by mortars and rocket fire.