Burma announced plans to free 56 political prisoners on Tuesday, in the latest amnesty ordered by President Thein Sein.
The identities of those pardoned was not immediately known, but officials said they include members of armed ethnic minority groups.
Dozens of dissidents remain jailed in the formerly military-ruled country, despite several rounds of presidential amnesties.
During a visit to London in July, Thein Sein promised to free all political prisoners by the end of the year. Critics have called for him to act immediately, saying the prisoners should not be used to win concessions from the West.
The latest amnesty came on the same day the Burmese leader headed to Brunei for a meeting of regional and international leaders.
Mark Farmaner with Burma Campaign UK said this is not a coincidence. "We've seen over the past two years that he's timed the release of political prisoners tactically in this way for good public relations before key international moments."
Tuesday's release included members of ethnic Shan and Kachin armed groups.
Analysts said they may have been freed to help convince Kachin rebels to join a nationwide cease-fire that Western nations have been demanding. The Burmese government opened a new round of peace talks with the Kachin Independence Army on Tuesday.
But Farmaner said many more dissidents are still being arrested. He doubts whether all political prisoners will be released by year's end.
"Levels of arrests of people for peaceful political activities is now at a five-year high. We haven't seen since 2008 this many people being arrested for taking part in peaceful political protests," he said.
Burma Campaign UK estimates that about 50 people have been arrested for peaceful political activities under Thein Sein's rule. It says about another 200 await trial.
A Burma-based group that also monitors the situation of political prisoners said the number of those arrested or awaiting trial is even higher.
Bo Kyi of the Assistance Association of Political Prisoners [AAPP] said he doubted that they all will be released by Thein Sein's end-of-year target date.
"It is unlikely to happen, because, according to our list, about 133 political prisoners remain and another 232 detainees are facing trials," he said. "Those trials need to be closed down and arbitrary detentions have to be stopped. Only then, the issue of political prisoners will end. Otherwise, as long as there are political prisoners and arrests, efforts to secure their release will continue."
The arbitrary jailing of political opponents was a hallmark of Burma's military rulers, who controlled the country for five decades until 2011.
Since then, a new, nominally civilian government has released hundreds of political prisoners, relaxed media censorship, and allowed opposition leader Aung San Suu Kyi to successfully run for parliament.
The reforms have won praise from Western governments, many of which have loosened decades-old economic sanctions against the Southeast Asian country.
VOA's Burmese service contributed to this report.