BREGA, Libya — An airstrike hit a convoy of Libyan military vehicles moving toward rebel lines outside the eastern oil port of Brega on Tuesday, rebels said as they regrouped outside the city. The regime, meanwhile, insisted Moammar Gadhafi won't step down but said it is ready to discuss changes in how the country is governed.

Backed by an international air campaign, the rebels have made inroads in recent days in eastern Libya. They advanced under artillery fire Monday and took part of Brega, an oil town that has changed hands several times since the fighting began last month.

Rebel officer Abdel-Bast Abibi said the two sides battled inside the city until nightfall, then the rebels moved back to the outskirts. It was a quiet night, but an airstrike struck early Tuesday as a convoy of eight Libyan military vehicles advancing toward the rebel positions, he said.

The strike hit two of the vehicles, prompting the others to turn around and race back into the city, carrying the bodies of slain pro-Gadhafi troops, Abibi said, citing surveillance teams. The report could not be independently confirmed.

Control of Brega's small refinery and Mediterranean port could significantly boost the rebels' hunt for revenues they can use to purchase heavy weapons for the fight against Gadhafi's better-equipped troops and militiamen.

About 100 rebels assembled on the eastern edge of Brega Tuesday morning with about six vehicles mounted with machine guns and rocket launchers, but it was unclear if they planned to move back into the city. The rebels recently have placed the front lines under the control of former military men, creating a more disciplined advance against Gadhafi's forces.

The government has softened its public stance against any compromise that would end the fighting, but government spokesman Moussa Ibrahim said any changes must be led by Gadhafi, who has ruled the country for more than four decades.

"We could have any political system, any changes: constitution, election, anything, but the leader has to lead this forward," he said late Monday in Tripoli.

He said Gadhafi, who took power in a 1969 coup, has no official position to relinquish but "has a symbolic significance for the Libyan people."

"Don't decide our future from abroad, give us a proposal for change from within," Ibrahim said, chastising Western powers who have a "personal problem with the leader" and economic interests they believe would be better served if Gadhafi's government collapsed.

The comments were unlikely to appease the rebels fighting to oust the Libyan leader who has a legacy of brutality. Any long-term settlement poses tough questions about the fate of Gadhafi's family and the new leader of a post-Gadhafi nation, and the opposition has rejected any solution that would involved one of his sons taking power.

The rebels also saw success Monday in their efforts to establish an internationally recognized government in eastern Libya, forging tighter links with Britain and Italy, both potentially major markets for Libyan oil. Italy offered diplomatic recognition to the Libyan opposition council, becoming the third country to do so after France and Qatar.

Italian Foreign Minister Franco Frattini also said the CEO of energy company Eni had visited the rebels' de facto capital, Benghazi, with the aim of resuming oil ties.

Rajab Sahnoun, a senior official with Arabian Gulf Oil Co., which runs an oil terminal in the eastern city of Tobruk, said the company was waiting for a Liberian tanker but was unsure when it would arrive. He did not say where the oil would be headed.

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In Benghazi, opposition spokeswoman Iman Bughaigis declined to provide any information on oil tankers coming to Libya.

The U.N. special envoy to Libya, Abdelilah Al-Khatib, told the U.N. Security Council Monday afternoon that pro- and anti-Gadhafi forces had clashed over the past few days in Zawiya, one of two western cities that rose up early in the revolt against Gadhafi.

He said there were unconfirmed reports of government shelling of towns southwest of Tripoli, an indication that resistance to the Libyan leader could be resurging in that area.

Al-Shalchi reported from Tripoli.