Thousands of Thai protesters gathered for a rally they say will be the final push in a six-month campaign to topple the government.
Eyewitnesses said more than 10,000 protesters had gathered at Government House in Bangkok.
Calls for the fresh demonstration and a march to the parliament ahead of a session planned for tomorrow came after a string of attacks at the cabinet office building.
Protesters have occupied the prime minister's office since late August.
The crowd led by the People's Alliance for Democracy plan to march to parliament early tomorrow. Police have erected barricades there and stationed trucks with water cannons.
Thailand's Prime Minister, Somchai Wongsawat, appealed for calm on Thai television, speaking from Peru, where he is attending a conference.
The PAD claims Mr Somchai is merely a puppet of exiled former leader Thaksin Shinawatra, his brother-in-law.
A government spokesman said they would not use force or weapons to disperse the demonstration, but that parliament would meet as planned.
Last Thursday, one protester was killed and 29 injured when a rocket-propelled grenade exploded in the middle of the Government House protest site, while eight protesters were injured yesterday by a similar bomb. There are reports that one of those has since died.
The PAD has blamed the government for both attacks, and called for supporters to join them today and tomorrow for a ‘last battle’ against the current administration.
The government has denied any link to the recent attacks, and Mr Somchai has promised a swift police investigation.
Police said about 10,000 pro-Thaksin supporters had come out to back the government, but leaders of that movement said they had no intention of confronting the PAD and said the rally ended peacefully this evening.
