Police hauled away about 20 opposition party members on Tuesday as their leader Aung San Suu Kyi waited for a decision from the ruling junta on whether it would release her or extend her five-year detention period.
Witnesses saw riot police shove members of the National League for Democracy into a truck as they were marching from the party's headquarters to Suu Kyi's home.
It was not immediately clear where the truck was headed. Security was stepped up around her villa as the junta faced a deadline to deal with her detention.
Nobel Peace Prize laureate Suu Kyi, who has been held under house arrest continuously since May 2003, has long been the symbol of the regime's brutality and the focus of a worldwide campaign that has lobbied for her release.
Her house arrest, which has been renewed annually, is believed to expire at midnight today, said Nyan Win, spokesman for her National League for Democracy party. With the regime saying nothing, there has been uncertainly about the exact expiration.
The ruling generals have given no sign they will release Suu Kyi, who has been confined for more than 12 of the past 18 years. Her latest period of arrest began in 2003.
The decision comes at a delicate time for the junta. It already is facing international condemnation for the way it failed the relief effort, with more than half of the 2.4 million survivors of Cyclone Nargis still desperately needing food, clean water and shelter more than three weeks after the disaster.