At least 15,000 anti-Thaksin demonstrators gathered at Bangkok's Sanam Luang (Royal Square) late Monday to call for the immediate resignation of caretaker Prime Minister Thaksin Shinawatra.
The demonstrators gathered at Sanam Luang since Monday afternoon, with many of them vowing to stay at the square through the night and then march to the Government House for urging the prime minister to step down.
About 8,000 policemen have been deployed around the square and other sensitive sites, such as the Government House and the Constitution Monument, which are seen as the political center of Thailand.
According to the schedule made by the rally office, the demonstrators will march to the Government House at 7:00 a.m. ( 0000 GMT) on Tuesday and some anti-Thaksin leaders will make speeches in front of the compound.
The army and police are both on high-level alert since pro- Thaksin groups from north-eastern Thailand will arrive in Bangkok early Tuesday and also make a rally outside the Government House. It will be the first-time face to face between the pro- and anti- Thaksin groups. A military source told Xinhua that a state of emergency could be declared in Bangkok if any violence during Tuesday's protest.