缅甸特赦囚犯迎接奥巴马到访
The Burmese authorities say than 452 prisoners will be released in a goodwill gesture, days ahead of a visit by US President Barack Obama.
缅甸当局称，美国总统奥巴马到访前几天，452名囚犯将被释放以示善意。
Mr Obama is expected to urge Burmese authorities to continue political reform
Political dissidents could be among those freed, but it is not clear how many.
Human rights groups say there are around 300 political prisoners.
Mr Obama's visit, the first by a serving US president, is intended to encourage the government to continue a reform programme begun last year.
Previous amnesties have included a many non-political prisoners.
Some foreign nationals were among those due to be released in the latest amnesty, state media said.
Continuing impunity
The military-led government's reforms have included abolishing pre-publication censorship and passing a law allowing peaceful protest.
The opposition National League for Democracy participated in parliamentary by-elections earlier this year, and swept the board.
Countries which previously had imposed sanctions on Burma have been offering deals on aid and increased trade links in response to the reforms.
However, Mr Obama's decision to make Burma one of his first destinations after being re-elected is being questioned by some critics, who say it is too soon to reward the government for reforms which have just started, the BBC's Jonathan Head reports from Bangkok.
They argue that the repeated promises by President Thein Sein that he will stick to the reformist path will only be credible when all political prisoners have been freed, our correspondent reports.
Dozens more people have been detained this year during various protests, and the Burmese military still acts with impunity（不受惩罚地） in border areas where it is fighting ethnic insurgents, he adds.
On a visit to India earlier this week, opposition leader Aung San Suu Kyi sounded a note of caution over the reform process, saying Burma had "not yet achieved the goal of democracy".