One of Libya’s top officials, meanwhile, abruptly made a "private visit" to Tunisia late Monday, according to the official news agency there. It is not clear if Libyan Foreign Minister Moussa Koussa was defecting, but it has raised suspicions over further cleavages within the embattled regime.

Rebel forces battled the government outside Muammar Qadhafi’s hometown and stronghold of Sirte as Western and Arab nations prepared to meet in London on Tuesday to seek an exit for Libya’s long time leader.

United Nations Secretary—General Ban Ki—moon, United States Secretary of State Hillary Rodham Clinton, the Arab League, the African Union and around 40 foreign ministers were scheduled to join the talks, seeking to ratchet up pressure on Col. Qadhafi.

Italian Foreign Minister Franco Frattini said several nations planned to put forward a deal which would propose a cease—fire, exile for Col. Gadhafi and a framework for talks, between Libya’s tribal leaders and opposition figures, on the country’s future.

One of Libya’s top officials, meanwhile, abruptly made a “private visit” to Tunisia late Monday, according to the official news agency there.

It is not clear if Libyan Foreign Minister Moussa Koussa was defecting, but it has raised suspicions over further cleavages within the embattled regime.

No representative from Libya’s opposition was expected to attend the conference, but an official familiar with planning for the talks said an envoy was expected to travel to London to meet with British diplomats on the sidelines. The official demanded anonymity to discuss the meeting with the opposition envoy ahead of a formal announcement.

Thanks to international airstrikes begun on March 19, Libya’s rebels are in a much stronger position than a week ago, having recaptured all the territory lost earlier to Col. Qadhafi’s forces, including two key oil terminals.

But the rebels remain woefully outgunned by Col. Qadhafi’s forces and it is unclear how they can take the stronghold of Sirte without further aggressive international air support. Attacks on Monday were repelled by heavy mortar and rocket fire.

Rebels acknowledged they could not have taken so much ground without the air and cruise missile strikes. Libya state television reported new NATO airstrikes after nightfall, targeting “military and civilian targets” in the cities of Garyan and Mizda about 40 miles and 90 miles respectively from Tripoli.

NATO insisted that it was seeking only to protect civilians and not to give air cover to an opposition march. But that line looked set to become even more blurred. The airstrikes now are clearly enabling rebels bent on overthrowing Qadhafi to push towards the final line of defence on the road to the capital.

There was growing criticism from Russia and other countries that the international air campaign is overstepping the bounds of the U.N. resolution that authorized it. The complaints came at a critical transition in the campaign from a U.S. to a NATO command. That threatens to hamper the operation, as some of the 28 NATO member nations plan to limit their participation to air patrols, rather than attacks on ground targets.

On Monday, rebel fighters moved about 70 miles (110 kilometers) west from the coastal oil terminal and town of Ras Lanouf to just beyond the small town of Bin Jawwad, where their push was halted by government fire along the exposed desert highway and the heavily mined entrance to Sirte.

The rebels are currently just 60 miles (100 kilometers) from Sirte, the bastion of Col. Qadhafi’s power in the centre of the country, beyond which is the largely rebel—held city of Misrata - and then the capital.

Sirte could therefore see some of the fiercest fighting of the rebellion, which began on February 15.

Some residents were fleeing Sirte, as soldiers from a brigade commanded by Col. Gadhafi’s son al—Saadi and allied militiamen streamed to positions on the city’s outskirts to defend it, witnesses said.

The city is dominated by members of the Libyan leader’s Gadhadhfa tribe. But many in another large Sirte tribe - the Firjan - are believed to resent his rule, and rebels are hoping to encourage them and other tribes there to help them.

Fighting in such a densely populated area is likely to complicate the rebels’ advance and add to the ambiguity of the NATO—led campaign, authorized by a Security Council resolution to take all necessary measures to protect civilians.

In Russia, which abstained from the U.N. vote, Foreign Minister Sergey Lavrov said strikes on Col. Qadhafi’s forces would amount to taking sides in what he called Libya’s civil war, and thus would breach the mandate that was initially envisaged as establishing a no—fly zone only to protect civilians.

But the inclusion of language allowing “all necessary means” opened the door to airstrikes and ship—fired cruise missile attacks on Col. Qadhafi’s forces to stop attacks on cities and cut supply lines.

Britain and France, which has been the most vocal supporter of the rebellion. In a joint statement, British Prime Minister David Cameron and President Nicolas Sarkozy of France said Qadhafi loyalists should abandon the dictator and side with those seeking his ouster.

“We call on all his followers to leave him before it is too late,” the two leaders said. “We call on all Libyans who believe that Qadhafi is leading Libya into a disaster to take the initiative now to organize a transition process.”

Col. Qadhafi is not on the defensive everywhere. His forces continued to besiege Misrata, the main rebel holdout in the west and Libya’s third—largest city. Residents reported fighting between rebels and loyalists who fired from tanks on residential areas.

Libyan officials took foreign journalists on a tour of the city’s outskirts but not into the centre, indicating government control did not extend far. Explosions and gunfire echoed through empty streets lined with burned out tanks and bullet—scarred buildings.

More In: International | News