Myanmar's leader has ordered a new prisoner amnesty ahead of a historic visit to the country by President Barack Obama on Monday.
State television said Sunday that President Thein Sein had ordered 66 detainees released, but it was not clear whether any political prisoners would be among them.
A Home Ministry official said that Thein Sein signed the amnesty order Friday, but the prisoners will be freed Monday. The official declined to be named because he is not authorized to speak to the press.
The presidential amnesty was the second announced this week.
On Thursday, Thein Sein announced an amnesty for 452 prisoners, but the move did not include prisoners of conscience and prompted activists to step up calls for the government to release those believed to remain behind bars.
Myanmar's government has long insisted that all prisoners are criminals and does not acknowledge the existence of political detainees. However, the reformist new government, praised for its moves toward democracy, has released hundreds of people this year who were jailed under the former military junta.
A separate press release, issued Sunday, said the government would initiate "initiate a process between the Ministry of Home Affairs and interested parties to devise a transparent mechanism to review remaining prisoner cases of concern by the end of December 2012."
The news came one day ahead of a visit Monday by Obama, who will become the first sitting American president to visit the once-pariah nation, also known as Burma.
Obama is due to meet Thein Sein, as well as opposition leader Aung San Suu Kyi before flying to Cambodia later Monday.
Thein Sein's administration has made freedom for political prisoners one of the centerpieces of its reform agenda. Earlier prisoner releases helped convince Western nations, including the United States, to ease sanctions they had imposed against the previous military regime.
Under the now-defunct junta, rights groups said more than 2,000 activists and government critics were wrongfully imprisoned.
Suu Kyi's party says at least 330 political prisoners remain incarcerated.
Obama said Sunday in Thailand that his visit to Myanmar is an acknowledgement of the democratic transition under way but not an endorsement of the country's government.
Obama's words were aimed at countering critics who say his trip to the country is premature.