More than 4,000 ethnic Tamils displaced by civil war left government-run camps Thursday, the latest to be released amid international criticism that Sri Lanka is moving too slowly to let thousands of others go.

Hundreds of thousands of minority Tamil civilians were forced into the camps after fleeing the final months of the government's decades-long war with the separatist Tamil Tiger rebels, which ended in May.

Rights groups have condemned the detention as an illegal form of collective punishment for the ethnic group. Aid groups say the camps are overcrowded and prone to disease, and fear imminent monsoons will create a public health crisis.

Sri Lanka has said that it can't release the Tamils until they are screened for rebel ties. The government also says that their villages must still be de-mined.

The at least 4,300 Tamils released Thursday piled on tractors and into buses to head home.

"We will take steps to give you all that you lost, other than the lost lives," Basil Rajapaksa, a senior adviser to his brother, President Mahinda Rajapaksa, told a public meeting in the village of Kathankulam.

Top government officials pledged to compensate the villagers for their losses but did not give specifics.

Sebastianpillai Rasanayagam, a 42-year-old rice farmer, was one of 1,225 refugees bused home to northern Mannar district.

He said his family had fled after a shell slammed into their house, killing his 8-year-old son.

The family crossed the front lines in February 2008 and was taken to a camp, where he described harsh conditions, including a lack of clean water.

"At the camp our only relief was that we were alive. We were worried when we will be able to return home," Rasanayagam said. "Hospital visits were the only times I got to go out."

Rasanayagam said he was relieved at being able to return home and resume farming, but he wept as he remembered his son.

"When I go home I will miss my son more," Rasanayagam said.

The United Nations, foreign governments and human rights groups have repeatedly asked Sri Lanka to release the estimated 270,000 people still detained.

Authorities said the 4,300 released Thursday are the first of 41,000 people who have been cleared to return home in four northern districts — Mannar, Jaffna, Kilinochchi and Mullaitivu.

The government promised a visiting U.N. official last month that it will send all the displaced people home by the end of January.