By Bill Hayton
BBC News, Hanoi
Vietnam's authorities have confined several prominent dissidents to their homes and cut off their phones, ahead of this weekend's Apec summit.
Hanoi has been spruced up for the Apec summit
Police guards have been placed outside the apartments of two lawyers who have spoken out against human rights abuses.
Other activists who have called for multi-party democracy have also been told not to leave their homes.
The move seems to be part of a general attempt to prevent anyone from disrupting the summit.
There's a heavy police presence in Hanoi at the moment - as might be expected given the imminent arrival of the Presidents of China, Russia and the US, among others, for the Asia-Pacific Economic Cooperation (Apec) forum.
It is particularly heavy outside the homes of critics of the Communist Party.
Two lawyers - Nguyen Van Dai and Le Thi Cong Nhan - have been banned from leaving their homes and had their telephones cut off.
Miss Cong Nhan's mother was told by police that her daughter cannot leave her apartment or talk to foreigners until next Monday - after the Apec summit has finished.
Dissidents say another colleague has been taken to a mental hospital and outside the home of another, Nguyen Khac Toan, police have placed a sign in English saying 'No Foreigners'.
The Vietnamese government has so far not responded to requests to comment on the police's actions.
Miss Cong Nhan is due to defend a British woman of Vietnamese origin potentially facing the death penalty for drug smuggling in a case which begins next Tuesday but she is barred from meeting her client.
The British Embassy says it is concerned about the restrictions and is seeking urgent clarification from the Vietnamese authorities.
Last weekend, a US-based rights group, Human Rights Watch, accused Vietnam of maltreating homeless children to improve the appearance of the capital, Hanoi, for visitors.
The group said the number of street children had visibly reduced in the run-up to the Asia-Pacific Economic Cooperation meeting.
Twenty heads of regional governments are scheduled to attend the summit.