Burma has started releasing 452 prisoners under an amnesty on Thursday, but pressure groups and relatives said that they have not yet heard of any political detainees being among those freed.
Activists said it was very disappointing and have accused the government of 'playing games'.
The government announced the move days before US President Barack Obama is set to visit Burma.
According to the BBC, since the end of military rule in 2011, hundreds of dissidents have been freed, but it is estimated that at least 300 are still in jail.
Many political detainees are in remote areas where communication is difficult, so the full extent of the releases may not be known for some time, the report added.
The Assistance Association for Political Prisoners (AAPP), a Thailand-based campaign group, said that the releases were 'the worst amnesty to date'.
Likewise, the New York-based Human Rights Watch (HRW) group and members of opposition leader Aung San Suu Kyi's National League for Democracy (NLD) cast doubt over the latest amnesty.
"It seems there is a new game in Burma, which is the political prisoners game," HRW deputy Asia director Phil Robertson said.
He described the non-release of political prisoners as 'cynical' and lacking in transparency.
Senior NLD representative Nie Nie accused the government of misinformation ahead of Obama's visit.
"They are lying to Obama about releasing political prisoners," he said, adding: "They did not release political prisoners."
The government earlier said that the releases were intended to "help promote goodwill and the bilateral relationship".
The move is the latest in a series of prisoner releases under the government of President Thein Sein. (ANI)