Libyan leader Muammar Gaddafi's forces on Sunday continued their bombardment of rebels in several cities including the eastern town of Ajdabiyah and the western city of Misrata.

Pro-Gaddafi troops on Sunday shelled the eastern edge of Ajdabiyah, where repeated explosions and machine gun fire could be heard.

Ajdabiyah, some 60 km from the oil town of Brega, and a strategic gateway to the rebels' stronghold Benghazi, was once home to about 150,000 people.

But four fierce battles between troops loyal to Gaddafi and the rebels in the past month have driven away waves of local villagers.

Also on Sunday, Libyan rebels said Gaddafi's troops killed six people during their bombardment of Misrata.

At least 47 people were also injured in the early morning bombardment of the insurgents' last major stronghold in western Libya, Abdel Basset Mezerik, a rebel spokesman, told Al-Jazeera TV.

As government troops are fighting a seesaw battle with the rebels in major towns across the country, the United States and its allies have started an intense search for a country willing to accept Gaddafi once the Libyan leader is forced out of power by NATO-led military operations.

The move came even though Gaddafi has shown defiance in recent days, declaring that he has no intention of yielding to demands that he leave his country, the New York Times reported on Sunday.

"The effort is complicated by the likelihood that he would be indicted by the International Criminal Court in The Hague for the bombing of Pan Am Flight 103 over Scotland in 1988, and atrocities inside Libya," the report said.

One possibility, the report quoted three administration officials as saying, is to find a country, possibly in Africa, that is not a signatory to the treaty that requires countries to turn over anyone under indictment for trial by the court.

And the officials hope that such a prospect could give Gaddafi "an incentive" to abandon his stronghold in Tripoli, the capital.

The NATO-led coalition has stated that Gaddafi must leave power though his ouster is not part of the military mission. The UN Security Council has authorized "all necessary measures" to protect the Libyan civilians but not to oust the leadership.

Of NATO's 28 member states, only six are joining the air raids on the ground targets of Libyan government forces with some 60 aircraft. As a stalemate continues on the ground, the military bloc is seeking at least eight additional warplanes from its members to sustain a longer-term operation and relieve strain on pilots flying repeated combat missions.

As the U.S. and its allies are seeking refuge for Gaddafi, a new wave of intelligence reports suggest that no opposition leader has emerged as a credible successor to him, the New York Times said.

U.S. officials conceded that the opposition leaders have not settled on who might succeed Gaddafi if he is ousted, and some fear that tribal warfare could break out if there is no consensus figure who could bind the country together.