Human Rights Watch has warned the Sri Lankan government against arbitrary detention of suspected opposition fighters, as the country prepares to free 130,000 Tamil refugees held in camps.
The international rights group said on Wednesday that it has been informed that some camp residents were told that they would be moved to other detention camps rather than be given the choice to be released.
Human Rights Watch (HRW) fears that such arbitrary detention of Liberation Tigers of Tamil Eealm (LTTE) suspects may increase, violating international law.
The internally displaced Tamils have been detained in state-run camps following the final stages of a military victory over the LTTE in the northeast of the country, which ended 25 years of civil war.
HRW also called for the about 11,000 LTTE suspects being already held in government centres to be either charged or released.
"The government's promise to release displaced civilians from camps is welcome, though long overdue," Brad Adams, HRW's Asia director, said.
"The government has been holding many Tamils for alleged involvement in the LTTE without providing them basic rights due under Sri Lankan and international law.
"The release of displaced persons should not be an excuse for another wave of arbitrary detentions."
Colombo announced last week that those in internally displaced camps would be allowed to leave by December 1. However, some people have since been told that they will be transferred to the Manik Farm centre in the north of the island nation.
New York-based HRW said that detainees have not been allowed access to legal council and their relatives have not been notified of their whereabouts.
Colombo did not immediately respond to the comments. It has previously said that LTTE fighters are being rehabilitated at the centres.
The government put displaced Tamils into camps following their military victory in May.
The LTTE had been battling the government for a separate ethnic-minority Tamil homeland in the northeast. More than 70,000 people died in the conflict.