TRIPOLI, Libya - Libyan leader Muammar Gadhafi urged world powers meeting on Tuesday in London to end their "barbaric" offensive against his oil-rich country, as rebels in the east set their sights on the key city of Sirte.

The Libyan leader likened the NATO-led air strikes targeting his artillery and ground forces to military campaigns launched by Adolf Hitler during World War II.

"Stop your barbaric, unjust offensive on Libya," Gadhafi said in the letter published by the state news agency Jana.

"Leave Libya for the Libyans. You are committing genocide against a peaceful people and a developing nation," he said in the letter addressed to the London meeting of more than 35 countries to map out the future for the north African country.

"It seems that you in Europe and America don't realize the hellish, barbaric (military) offensive which compares ... to Hitler's campaigns when he invaded Europe and bombed Britain," Gadhafi said.

The air offensive was launched on March 19 by the United Kingdom, France and the United States to enforce a UN no-fly zone over Libya and to protect civilians under attack by government forces.

The UK, France, Germany and the US have agreed that the London talks should aid "the political transition in Libya", said a French presidency statement.

UK Prime Minister David Cameron and French President Nicolas Sarkozy said ahead of the meeting that the current Libyan government had lost all legitimacy.

"Gadhafi must therefore go immediately. We call on all his followers to leave him before it is too late," a joint statement said.

In a pre-meeting video conference with his fellow leaders on Monday, Cameron said he hoped the summit would "strengthen and broaden the coalition of countries committed to implementing the UN resolutions".

On the ground, rebels who launched their uprising against Gadhafi's four-decade rule in mid-February were regrouping on Tuesday after being pummeled by loyalist forces at the village of Harawa, 60 kilometers from Sirte, Gadhafi's birthplace.

Emboldened by the Western air strikes that allowed them to overrun the strategic town of Ajdabiya on Saturday, the rebels raced west toward Sirte before Monday coming heavy artillery attack first at Bin Jawad, 140 km from Sirte, and then, at nightfall, at Harawa.

Al Jazeera television showed pick-up trucks crowded with fighters toting Kalashnikovs on Tuesday morning heading east toward the front lines.

Coalition warplanes were again in action late on Monday after darkness fell, bombing government targets on the central coast and in the west, but US officials denied the military action was intended directly to help the rebels.

Libyan Deputy Foreign Minister Khaled Kaim accused the coalition forces of wanting to cut the country in two, in comments broadcast on Italian television late on Monday.

"The tactic of the coalition is to lead to a stalemate to cut the country in two, which means that the civil war is a continuous war, the start of a new Somalia, a very dangerous situation," he told Rai Uno.

Agence France-Presse