UN envoy Walter Kalin (C) arrives at a camp for displaced in Vavuniya, north east of Colombo, Sri Lanka, 25 Sep 2009Over the coming weeks, the Sri Lankan government plans to release nearly 40,000 ethnic Tamils confined in military run-refugee camps. The first group has already left the camps. The government has also come under renewed international pressure to investigate charges of war crimes during the final stages of its military campaign to end a civil war waged by Tamil Tiger rebels.

Sri Lankan officials say a batch of 6,000 Tamils has left the country's largest refugee camps in the north to return to their villages. This is the largest single group allowed to go home since a military campaign to defeat the Tamil Tiger rebels ended this May.

It is also the first time that the government allowed refugees to return to areas which were formerly controlled by the rebels.

The final stages of the fighting displaced nearly a quarter of a million Tamils, who are housed in crowded camps in the north. Until Thursday, only a small number had been freed.

The slow pace of their release has triggered international concern and frequent appeals by the United Nations and rights groups to let the refugees return to their villages.

U.N. spokesman in Colombo, Gordon Weiss, says the government is making an effort to speed up the pace of resettlement.

"We have detected certainly an increase in the past couple of weeks of the rate at which people are being allowed to return home," said Gordon Weiss. "They are making a serious attempt now to get people out of the camps and get them back to their villages."

The government says that over the coming weeks it will release 40,000 refugees. It says it has detained the refugees because it wants to screen them to weed out former rebels, and to demine villages where battles had raged.       

The government is also facing international pressure to investigate alleged war crimes. This week, a probe by the European Union found Sri Lanka in breach of human rights laws during the military campaign to defeat the rebels. A US state department report has called on Sri Lanka to investigate alleged rights abuses in the closing stages of the conflict, and punish those responsible.  

So far the government has rejected such allegations saying the evidence is unsubstantiated.   

But several independent voices in Sri Lanka are backing the calls by the US and the European Union.

The head of Colombo's Center for Policy Alternatives, Paikiasothy Saravanamuttu says an investigation into alleged war crimes will help to heal the wounds of the civil war.

"The key point here is, can we have reconciliation without accountability," said Paikiasothy Saravanamuttu. "We are talking about reconciliation, we are talking about moving ahead. Allegations left uninvestigated with regard to crimes of this nature, violations of human rights, will only serve to feed resentment, bitterness, anger, frustration."  

The Tamil Tigers struggle for an independent homeland was triggered by complaints of discrimination against the minority Tamil community by the majority Sinhalese.