British Prime Minister David Cameron and French President Nicolas Sarkozy gave Libya's new rulers strong support during a landmark visit to Tripoli on Thursday.

They vowed to release billions of dollars more in frozen assets and to push ahead with NATO strikes against Moammar Gadhafi's last strongholds.

Cameron told the fugitive Libyan leader and his backers, "It is over. Give up."

The two were the first world leaders to travel to Tripoli since revolutionary forces, backed by NATO airstrikes, swept into the capital and forced Gadhafi into hiding. The visit aimed to give a significant boost to the National Transitional Council, the body of former rebels that is widely recognized as the new leadership but faces a major struggle in establishing its authority.

At a press conference alongside NTC chief Mustafa Abdul-Jalil and the NTC's prime minister Mahmoud Jibril, Cameron and Sarkozy both expressed their backing for the council.

Cameron said he would push for the release to the NTC of billions of dollars in Libyan assets that had been frozen to punish Gadhafi's regime. To that end, he announced Britain would introduce a draft resolution to the UN Security Council on Friday authorizing the release of all Libyan assets.

Cameron also pledged the NATO mission would continue as Gadhafi loyalists are still battling revolutionary forces on three fronts in central and southern Libya. "There are still parts of Libya under Gadhafi's control, Gadhafi is still at large, and we must make sure this work is completed," he said.

He called on all the holdouts to stop fighting.

Lucrative trade, oil deals

Britain and France led international support for the rebellion and their countries were major contributors to NATO airstrikes that helped turn the tide in favour of the opposition.

All that support could put France and Britain in a good position to cash in on lucrative trade and oil business once the country gets on its feet, but Sarkozy denied that was the goal.

"We ask for no preference with respect to Libyan assets or resources. What we did we did without a hidden agenda, but because we wanted to help Libya," Sarkozy said.

The NTC said Thursday its foreign allies would have preferential access to future business deals within a "framework of transparency," according to a report from Reuters. It also said there had been no prior agreements signed with its "allies and friends."

Sarkozy also said Gadhafi and others who "committed crimes" will be brought to justice but urged Libyans to avoid "vengeance" and seek unity and reconciliation.

The NTC and an executive committee it created are largely made up of technocrats — some of whom were once would-be reformers in Gadhafi's regime who grew disillusioned and left — and representatives from town and cities around the country.

It not only faces the task of winning control over the last Gadhafi strongholds, it also must rein in the numerous armed groups and factions under the former rebel umbrella.

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An anti-Gadhafi fighter guards a checkpoint about a kilometre north of the besieged city of Bani Walid, one of Gadhafi's few remaining strongholds. ((Zohra Bensemra/Reuters))

The flow of more of the frozen funds from abroad could boost its hand.

A Cameron spokeswoman, who spoke on condition of anonymity in line with policy, said a new United Nations Security Council resolution authorizing the release of all frozen Libyan assets has support of all five permanent members.

Britain has also won approval from the U.N. sanctions committee on Libya to release a further $950 million immediately to fund public sector salaries, she said.

Britain will also offer funds for weapons decommissioning, mine clearance, medical assistance for those with grave combat injuries and specialist help in locating and secure chemical weapons.

Fighting reported near Sirte

NATO forces continued to go after the holdout loyalist forces. Airstrikes hit targets 24 targets on Wednesday, including several radar systems and surface-to-air missile systems near the three main strongholds of Gadhafi's supporters — his hometown of Sirte, Bani Walid and Sabha — as well as smaller holdouts Waddan and Zillah, the alliance said.

Libyan revolutionary forces spokesman Ali Gliwan says fighters on Thursday crossed a major highway overpass, known as al-Gharbiat, at the southwestern entrance of Sirte.

He said the fighters are encountering some resistance and have come under rocket fire. He says one fighter was killed.