Thailand's prime minister has avoided anti-government protests outside his offices and slipped through barricades as demonstrators continued to demand he dissolve parliament and call fresh elections.

With hundreds of protesters camped outside Government House, a car carrying Abhisit Vejjajiva entered the compound in Bangkok through a side entrance, witnesses said on Wednesday.

Abhisit had earlier returned to the Thai capital after a rally by more than 10,000 red-shirted anti-government protesters forced him to move Tuesday's weekly cabinet meeting to the seaside resort town of Hua Hin.

Many of the protesters - supporters of Thaksin Shinawatra, the former prime minister ousted in a 2006 coup – had vowed to camp outside the building until their demands were met.

But overnight numbers dwindled to less than 1,000, a police official told AFP news agency.

The so-called "Red Shirt" protesters have campaigned against the government since a court order ousted the previous government made up of Thaksin allies.

Protest leaders have said they will stay outside Government House for at least three days.

Political turmoil

Aside from dissolving parliament, the "Red Shirts" also want the government to prosecute leaders of the rival "Yellow Shirts", whose protests closed down Bangkok's two main airports late last year, and sack Kasit Piromya, the Thai foreign minister.

Piromya was a vocal supporter of the anti-Thaksin protesters, known as the People's Alliance for Democracy (PAD).

Last year hundreds of PAD supporters occupied Government House for three months, triggering a series of clashes with police during which two people were killed.

The group also seized control of Bangkok's two airports for a week in late November.

The protests are the latest move in months of political turmoil that has swept Thailand, and threatens to further undermine confidence in an economy already reeling from the effects of the global financial crisis.