YANGON - Myanmar's government said on Saturday 302 of the 651 detainees it freed this week were political prisoners whose release had been sought by the National League for Democracy (NLD) party of Nobel peace laureate Aung San Suu Kyi.

They were freed so they can play a part in the political process, Home Minister Lieutenant-General Ko Ko told reporters, suggesting they might be allowed to run for parliament despite their prison records, one of the demands of rights groups such as Human Rights Watch.

The government had not previously spelt out how many of those released on Friday under its amnesty were political prisoners, although it was clear that many prominent dissidents were among them.

Western governments welcomed the move and the United States, which has made the freeing of political prisoners a condition for lifting economic sanctions, immediately said it would begin the process of exchanging full ambassadors for the first time in 20 years.

"Organisations and associations at home and abroad demanded the release of prisoners of conscience after sending in the list they had compiled," Home Minister Ko Ko told reporters. "A total of 302 were granted amnesty, after examining the list of 604 sent by the NLD," he said. Of those on the NLD list, 107 had already been freed, the credentials of 51 could not be checked.