The fighting comes after the United States accused some NATO allies on Friday of failing to pull their weight in the campaign against Muammar Gadhafi's forces, as the Libyan leader kept up shelling of the rebel-held town of Misrata.

"The mightiest military alliance in history is only 11 weeks into an operation against a poorly-armed regime in a sparsely-populated country - yet many allies are beginning to run short of munitions, requiring the US, once more, to make up the difference," US Defense Secretary Robert Gates said in a valedictory speech at NATO headquarters in Brussels.

Gates's exasperation has been echoed by rebels, who control the east of the country and some other areas but do not appear to pose an imminent threat to Gadhafi's rule.

Turkish Gadhafi Guarantee

Turkey, which is a member of NATO, said Gadhafi had no way out, but to leave Libya and offered the him an exit.

"We ourselves have offered him this guarantee, via the representatives we've sent. We told him we would help him to be sent wherever he wanted to be sent. We would discuss the issue with our allies, according to the response we receive. Unfortunately we still haven't got a response from Gadhafi."

US Secretary of State Hillary Clinton, appearing at the Abu Dhabi meeting of the Libya contact group on Thursday, said talks were under way with people close to Gadhafi who had raised the "potential" for a transition of power but added: "There is not any clear way forward yet."

Under pressure to come up with plans for a transitional government while still in disarray, the rebels have said the onus is on foreign powers to hasten assistance.

"Our people are dying," rebel Oil and Finance Minister Ali Tarhouni said. "So my message to our friends is that I hope they walk the walk."

Gadhafi describes the rebels as al Qaeda terrorists and says foreign intervention is a front for a grab at the country's oil.

Mikhail Margelov, Russia's Africa envoy, who travelled to Benghazi on Friday, said he would go to Tripoli as soon as NATO provided a corridor through its Libyan no-fly zone.