"If their movement harms the peace and tranquillity of the state and leads towards unrest in the country, we will take action -- not only prevention, but detention and questioning," Information Minister Brigadier General Kyaw Hsann said at a press conference.

"We have to prevent a fire hazard. It's the duty of the government to protect the state and the people from the danger of terrorist acts by destructive elements," Kyaw Hsann said.

More than 100 pro-democracy activists are holding a week-long prayer vigil at Shwedagon pagoda in Yangon, calling for peace in a rare public protest.

The vigil follows a petition drive that organizers say collected 530,000 signatures, calling for the release of the nation's estimated 1,100 political prisoners, including detained democracy icon Aung San Suu Kyi.

The campaign began one month ago, after six pro-democracy activists were arrested in late September, including five former student leaders who participated in a pro-democracy uprising in 1988.

The junta has dismissed the petition, and accused organisers of faking the signatures.