Myanmar security forces have surrounded the headquarters of the ruling Union Solidarity and Development Party in the capital, Naypyitaw, and prevented party members in the compound from leaving, party sources in the building said on Thursday.
Several trucks of soldiers and police officers arrived at the compound at around 10 p.m. on Wednesday evening, the sources said.
"We have not been allowed to move around since late yesterday," said one party member.
Tension has risen between leaders of the military-backed government over the selection of candidates to run in a Nov. 8 general election, the sources said.
Government spokesmen were not available for comment.