Sri Lankan authorities say they have opened up huge camps holding people detained since the army's victory over Tamil Tiger rebels earlier this year.
The general in charge of Menik Farm, the biggest camp, told the BBC people were free to leave - after giving their details so they could be monitored.
The closed, military-run camps house more than 130,000 people.
Sri Lanka has drawn strong international criticism for holding people there against their will.
They were set up for people fleeing the war zone during the government's final offensive against the Liberation Tigers of Tamil Eelam (LTTE). The decades-long conflict was declared over in May.
There have been severe restrictions on access to the camps, and international media organisations have not been allowed to visit them in recent weeks.
The United Nations has welcomed the decision.
But with northern Sri Lanka devastated and strewn with mines, it's expected some of the displaced will want to stay on in the camps for now.