Thai Prime Minister Abhisit Vejjajiva evaded anti-government protesters camped outside his offices on Wednesday and slipped into work under heavy police protection, an AFP correspondent saw.
Up to 10,000 supporters of ousted premier Thaksin Shinawatra dressed in their trademark red shirts surrounded Bangkok's Government House compound on Tuesday demanding fresh elections, and many camped outside overnight.
But numbers had dwindled to less than 1,000 by early on Wednesday, a police official said, allowing Abhisit to cross a bridge by car and enter the compound protected by police and soldiers at about 7:00am (0000 GMT).
"On Wednesday the prime minister and I are able to work as normal, thanks to protesters who did not violate the law and also thanks to officials who carried out their work with patience," said deputy premier Suthep Thaugsuban.
The "Red Shirts" have campaigned against the government since a court dissolved the pro-Thaksin former ruling party in December, paving the way for British born Abhisit to take power in a parliamentary vote.
Tuesday's rally forced Abhisit to move his weekly cabinet meeting to the beach resort of Hua Hin, where he will host a summit of Association of Southeast Asian Nations leaders from Friday.
Protest leaders have said they will stay outside Government House for at least three days, but have vowed not to disrupt the Hua Hin summit.
As well as calling for the dissolution of parliament, they are demanding the resignation of Foreign Minister Kasit Piromya because of his links to anti-Thaksin group the People's Alliance for Democracy (PAD).
They also want PAD leaders charged for their occupation of Bangkok's two airports late last year, the peak of six months of protests aimed at toppling the pro-Thaksin government elected in December 2007.