Libyan rebels fighting to oust Moammar Gadhafi have looted shops and clinics and torched the homes of suspected regime supporters in some of the towns they seized in the country's western mountains, Human Rights Watch said Wednesday.
The findings come as the rebels have enlarged the area under their control in the west and inched closer to a key supply route to Tripoli.
NATO has been bombing Gadhafi's forces and military sites to enforce a U.N. resolution to protect civilians. Still, the civil war has fallen into a virtual stalemate, with neither side able to make significant progress in recent weeks.
Rebel leaders visiting NATO headquarters in Belgium, meanwhile, denied that there had been any negotiations with the Libyan government about a diplomatic end to the conflict and called for continued airstrikes, even during the upcoming holy month of Ramadan.
The Human Rights Watch report, based on interviews with local fighters and residents, said that after seizing towns, rebel forces burned down a number of homes believed to belong to Gadhafi supporters and carted out supplies from stores and medical facilities.
The spokesman for the rebel National Transitional Council based in Benghazi, more than 600 miles (1,000 kilometers) away, denied at first that anti-Gadhafi fighters were involved.
"These acts were carried out by individuals who don't represent the NTC nor the February 17 revolution," he said, referring to the anti-Gadhafi uprising.
He acknowledged, though, that it "could be a mistake" and said if there was evidence, those involved would be brought to justice.
In one case cited by the report, the rights group witnessed five houses on fire in the village of Qawalish, which was seized by the rebels on July 6, and gunmen loading their truck with supplies looted from a shop.
A few days later, nine more houses had been set alight.
HRW said clinics in three other towns were also looted and vandalized.
"We basically took everything," a rebel medic in Awaniya told the New York-based group.
The alleged violations by the rebel fighters, mostly armed civilian volunteers with a loose command structure, raise concerns about retaliatory violence as Gadhafi clings to power from his base in the capital, Tripoli.
The reports also throw NATO in an awkward position, since the stated goal of their air campaign against government forces is to protect civilians.
Also Wednesday, Libya's prosecutor general accused NATO of killing 1,108 people with its airstrikes and wounding another 4,500 and filed charges against the alliance's chief in Libyan court.
"As the prosecutor general responding to the calls of the Libyan people I have decided to purse criminal procedures against the secretary general of NATO," said Mohammed Zikri al-Mahjoubi. "Nothing can explain the crimes and actions of NATO on Libyan soil .. it cannot be described as a crime, it is something exceptional and unprecedented."
He outlined 10 charges, including the attempted assassination of Gadhafi, and described the air campaign as genocide against the Libyans.
For his part, alliance head Anders Fogh Rasmussen told visiting rebel leaders that NATO would continue its bombing campaign in Libya as long as Gadhafi's forces threaten civilians.
Rights groups have accused Gadhafi's forces of violations, too, including indiscriminately shelling civilian areas, abusing detainees and laying land mines.
Since the uprising seeking to end Gadhafi's nearly 42-year rule broke out in mid-February, armed rebels have seized control of much of the country's east, where they've set up an administration in Benghazi. They also control the coastal city of Misrata and much of the Nafusa mountain range southwest of Tripoli.
HRW called on rebel commanders to hold their forces responsible for damaging civilian property.
"Opposition forces have an obligation to protect civilians and their property in the areas they control so people feel they can return home safely and rebuild their lives," said Joe Stork, the group's deputy Middle East and North Africa director.
Rebel commanders in the western mountains could not be immediately reached for comment.
HRW quoted one commander as acknowledging that some abuses had taken place, but denying that such acts were policy.
"If we hadn't issued directives, people would have burned these towns down to the ground," the group quoted Col. El-Moktar Firnana as saying.
Hubbard reported from Cairo. Associated Press writer Rami al-Shaheibi in Benghazi, Libya contributed to this report.