BENGHAZI, Libya - The United States has launched a diplomatic offensive against Libya among African nations as Tripoli accused NATO of a "massacre" of 85 villagers in airstrikes in support of rebels.

US diplomats are visiting several African countries as part of efforts to urge leaders to press Libyan leader Muammar Gadhafi to leave power immediately, officials in Washington said on Tuesday.

Several African states have been reluctant to call for him to step down and have criticized the NATO-led military campaign in Libya.

Gene Cretz, the US ambassador who left Tripoli after Gadhafi launched his crackdown on the opposition in February, and Principal Deputy Assistant Secretary of State Donald Yamamoto arrived on Monday in Addis Ababa, headquarters of the African Union (AU), State Department deputy spokesman Mark Toner said.

They "are in Africa to meet with African Union members to discuss the crisis in Libya and the need for Gadhafi to relinquish power now", he said.

Toner said they met Ethiopian Prime Minister Meles Zenawi and would meet AU Chairman Jean Ping. They also met Mahmud Jibril, leader of Libya's opposition National Transitional Council who was visiting Ethiopia.

Gadhafi, meanwhile, said world powers would be held responsible for the "ugly massacre committed by NATO" on the village of Majer where 85 people were killed, Libya's official JANA news agency reported.

NATO attacked Majer, 10 kilometers south of Zliten, which is 120 km east of Tripoli, trying to help rebel fighters enter the government-held city from the south, government spokesman Mussa Ibrahim said.

"After the first three bombs dropped around 11 pm on Monday, many residents of the area ran to the bombed houses to try to save their loved ones. Three more bombs struck," he told reporters.

Thirty-three children, 32 women and 20 men from 12 families were killed in the "massacre", Mussa said.

Reporters attended the funerals of victims and saw 28 bodies buried at the local cemetery where hundreds of people vented their anger against NATO, an AFP correspondent said.

However, NATO spokesman Colonel Roland Lavoie denied reports of heavy civilian casualties, saying that the alliance's aircraft only bombed a "military target" on Monday near the city of Zliten.

"The target was two former farm buildings, which had been taken over by pro-Gadhafi forces and transformed into a field military complex," he said, adding NATO had no "evidence of civilian casualties at this stage".

AFP-Xinhua