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Myanmar's reformist government ordered more than 450 prisoners freed Thursday in an amnesty apparently intended as a goodwill gesture ahead of a historic visit by President Barack Obama next week.

It was not clear whether any political prisoners will be among those released, but past amnesties have included both prisoners of conscience and common criminals.

The administration of President Thein Sein has made freedom for political prisoners a centerpiece of its reforms over the last year and a half to seek international favor after almost five decades of repressive army rule. Earlier amnesties helped convince Western nations, including the United States, to ease sanctions they had imposed against the previous military regime.

The announcement in the state-run New Light of Myanmar newspaper comes just days before Monday's planned visit by Obama, who will become the first sitting American head of state to visit the country.

Under the now-defunct junta, which ceded power to an elected government in 2011, rights groups said that more than 2,000 activists and government critics were wrongfully imprisoned.

Myanmar's main opposition movement estimates that at least 330 political prisoners are incarcerated, according to Nyan Win, a spokesman for Aung San Suu Kyi's National League for Democracy party.

Nyan Win said he believes the latest amnesty was "a goodwill gesture" ahead of Obama's trip. "We want all political prisoners to be freed," he added.

Prominent activist and former detainee Ko Ko Gyi echoed the criticism of rights groups who accuse Thein Sein of using strategically timed prisoner releases to appease the international community.

"The release of prisoners of conscience should not be used as a bargaining chip," said Ko Ko Gyi, a leader of the country's 1988 pro-democracy uprising who spent many years in prison. The last amnesty took place in September, a week before Thein Sein visited New York for the U.N. General Assembly.

State media said some of the prisoners to be released Thursday were foreigners who would be extradited, but it gave no details.

Thein Sein's government has spearheaded a major transition toward democracy in the Southeast Asian nation, easing harsh media censorship, signing cease-fire deals with armed rebel groups, and helping opening the country to Western investment.