Myanmar on Tuesday declared it would have "no more political prisoners" by year-end after announcing a sweeping amnesty, releasing several inmates as campaigners voiced concern that more dissidents remain behind bars.
The country, which had pledged to free all prisoners of conscience by the end of 2013, has held a series of high-profile amnesties as part of dramatic reforms since the end of outright military rule nearly three years ago.
It was unclear whether the amnesty would affect all of about 40 political prisoners listed by campaigners, as well as a further 200 people awaiting trial, mainly for protesting without permission.
Myanmar late Monday said it would pardon those imprisoned under controversial legislation, including the Emergency Act used by the junta to imprison opponents as well as laws governing freedom of assembly and the right to protest.
Presidential spokesman Ye Htut said the amnesty, along with a separate pardon for five additional inmates jailed under other legislation, meant "there are no more political prisoners".
"I would like to say that the president has fulfilled his promise given to the people, because there will be no political prisoners at all at the end of 2013," he said in a post on his Facebook page, without giving further details of the release which began Tuesday.
Former general Thein Sein has won international plaudits and the lifting of most western sanctions for overseeing political and civil freedoms since becoming president nearly three years ago.
But campaigners sounded a note of caution.
"We cannot say at this moment whether there are no more political prisoners. We are waiting and watching," said Thet Oo, of a group representing former political prisoners in Yangon, adding he hoped more activists would be released in coming days.
He said five political prisoners were thought to have been released across the country Tuesday.
Around 120 more people awaiting trial -- some of whom were being held in prison -- were believed to have had cases against them dropped.
Arbitrary imprisonment was a hallmark of nearly half a century under a junta that denied the existence of political prisoners, even as it imposed harsh punishments on rights activists, journalists, lawyers and performers.
Before Myanmar's reforms, rights groups accused the country of wrongfully imprisoning about 2,000 political detainees.
Most of these have since been freed under previous amnesties, but many political prisoners have suffered repeated arrests for continuing their activities.
Nyan Win, spokesman for Aun San Suu Kyi's opposition National League for Democracy party, welcomed the amnesty and said it would "technically" mean there were no more political prisoners.
"We have to say that there are no prisoners under political charges. But we also have to check if there are people remaining in prison under other charges," he told AFP.
Dozens of relatives and friends awaiting news of their loved ones gathered outside Yangon's notorious Insein prison, where at least nine inmates were freed Tuesday.
It was unclear how many of them were considered political prisoners.
Peace activists Yan Naing Tun and Aung Min Oo, who were sentenced in recent weeks to eight months in prison for marching to the rebel town of Laiza in strife-torn northern Kachin state, were greeted by jubilant supporters as they walked free from the jail.
"I respect the president for keeping his promise," Yan Naing Tun told reporters.
The latest amnesty includes those convicted under the most notorious laws used by the former junta against its critics, including democracy campaigner Suu Kyi -- who is now an MP following the dramatic reforms.
But while the pardon appears to cover those currently facing charges, it does not extend to people arrested after December 31.
David Mathieson, a researcher with New York-based Human Rights Watch, said the claims could be "bluster" to try to meet the self-imposed release deadline.
He called on Myanmar to repeal the controversial laws.
Campaigners fear authorities could continue to arrest critics in the future, potentially creating more political prisoners.
Prison authorities said they did not have a timetable for releasing those pardoned, adding it could take time to identify all those affected.