Burma is still holding more than 1,100 political prisoners, despite the release of dozens of dissidents in July, a UN rapporteur has said.
Aung San Suu Kyi has spent nine of the last 16 years under arrest
Paulo Sergio Pinheiro told the UN General Assembly that Burma's military junta also routinely used torture.
Mr Pinheiro said that such detentions undermined the junta's 2003 commitment to a transition to democracy.
Burma's most prominent political prisoner, opposition leader Aung San Suu Kyi, remains under house arrest.
Mr Pinheiro, UN special rapporteur on Burma, has not been allowed to visit Burma since November 2003, but has based his report on information from various independent sources.
Monks, lawyers, teachers, journalists, farmers, politicians, student leaders, writers and poets are among those being held for their political views, he said.
"Civilians, including members of registered political parties and pro-democracy activists, continue to be harassed, arrested, tried and sentenced to prison for the peaceful exercise of basic civil and political rights and freedoms," he said.
Several high-profile dissidents were among 249 political prisoners released on 6 July, but Mr Pinheiro expressed disappointment that U Win Tin, a 75-year-old editor and poet imprisoned for 16 years, had been promised release on that date but remains in Burma's notorious Insein prison.