The head of Libya's National Transitional Council has asked members of the U.N. Security Council to lift remaining sanctions on Libya.

Libya's interim Prime Minister Mahmoud Jibril told the council in New York Monday that sanctions are hindering the NTC's ability to provide basic needs for citizens. The Security Council already has unfrozen $16 billion in Libyan assets, and the NTC hopes to gain access to more assets that remain locked.

Libya's NTC fighters continue to battle for control of Moammar Gadhafi's last remaining strongholds.

On Sunday, NTC fighters pushed into Sirte's center but met stiff resistance in Mr. Gadhafi's hometown from forces loyal to him. The fighters later withdrew to clear the way for NATO airstrikes.

NATO warplanes pounded Sirte Sunday, striking a radar facility, ammunition storage site and several other targets. NATO said alliance forces were bombing loyalists in Sirte after reports emerged of “executions, hostage-taking and the targeting of individuals within the city.”

An NTC military spokesman said an attack Sunday on Ghadames, about 450 kilometers southwest of Tripoli, was carried out by fighters belonging to a unit that had been under the command of Mr. Gadhafi's son, Khamis, who was reported killed in earlier clashes.

Also, Libya's interim rulers say they have found a mass grave believed to hold the remains of 1,270 inmates killed by security forces in a notorious 1996 massacre.

Investigators used information obtained from witnesses and former Gadhafi officials to find the field scattered with bone fragments at Tripoli's Abu Salim prison. Authorities believe the bodies were kept in the prison before they were buried in 2000 just outside the building's walls.

Most of the inmates killed were political prisoners, including Islamic clerics and students who had dared to speak out against Mr. Gadhafi. In June 1996, they rioted to protest conditions at the facility and were gunned down by forces directed by some of Mr. Gadhafi's inner circle.

Lingering anger over the massacre, among other things, ignited the uprising against Mr. Gadhafi in February — when families of the inmates killed at Abu Salim demonstrated in the eastern city of Benghazi to demand the release of their lawyer.

NTC forces are trying to determine Mr. Gadhafi's whereabouts.