COLOMBO, Sri Lanka (AP) — A government-appointed commission looking into Sri Lanka's civil war began public hearings Wednesday amid international skepticism about its credibility as it has no mandate to investigate allegations that thousands of civilians died in the final months of the conflict.

The United Nations says at least 7,000 civilians were killed in the last five months before the war ended in May 2009 when government forces finally crushed ethnic Tamil rebels who had been fighting for an independent state for a quarter-century. The rebels had claimed marginalization of minority Tamils by ethnic Sinhalese-controlled governments.

President Mahinda Rajapaksa appointed the commission in May, a year after the end of the war, to determine why a Norway-brokered cease-fire signed by the government and Tamil Tigers in 2002 collapsed and who was responsible.

Human rights groups say the commission is aimed at deflecting calls for an international probe of alleged war crimes, including government shelling of civilians and other issues.

In June, U.N. Secretary-General Ban Ki-moon appointed a three-member panel to advise him on ensuring accountability for the alleged abuses during the war.

Sri Lanka has refused to cooperate with the panel or issue visas for its members, saying an external panel is an infringement of the country's sovereignty.

Commission Chairman C.R. de Silva said in his opening remarks Wednesday that the time had come to "consolidate the military victory by addressing the root causes of the conflict and establish national integrity and reconciliation."

The commission began its hearings with presentations by the former Sri Lankan ambassador to the U.S., Bernard Gunatillake, and a former government peace negotiator with the Tigers.

Gunatillake said that the Tigers were not sincere in peace talks that followed the 2002 cease-fire and were buying time for another war.

The government has accused the rebels of having used the truce to smuggle in weapons, including a set of small airplanes, by sea, and to build berms and other defenses around their stronghold in the north of the island.

Gunatillake called for the immediate resettlement of tens of thousands of war-displaced civilians still living in camps and the return of private land and houses occupied by the army as important steps for long-term peace.

Hearings also will be conducted in ethnic Tamil areas to allow people there to air their grievances, de Silva said.

The hearings will be held in public except when witnesses ask for a closed session or when sensitive security details are discussed, he said.

In addition to accusations of indiscriminate shelling, rights groups have also accused government forces of having blocked access to food and medicine for minority Tamil civilians trapped in the war. The rebels have been accused of holding civilians as human shields, killing those trying to escape the violence and forcibly recruiting children as fighters.

The International Crisis Group think tank said in a report early this year that at least 30,000 civilians could have died in the last phase of the war. It said it calculated the figure by comparing the original population of the war zone with the number who escaped the fighting.

On Tuesday, a group of 57 U.S. lawmakers wrote to Secretary of State Hillary Rodham Clinton urging her to push for an international investigation of war crimes allegedly committed by Sri Lankan government forces and the Tamil Tigers. The lawmakers said the Sri Lankan commission had a narrow scope and no mandate to investigate abuses.