Hundreds of anti-government protesters have forced their way into Thailand's Election Commission building, a witness says, raising the stakes in a four-week rally aimed at toppling the government.
The red-shirted protesters, supporters of ousted Prime Minister Thaksin Shinawatra, have also occupied Bangkok's main shopping district.
They are attempting to force Prime Minister Abhisit Vejjajiva to dissolve parliament and call elections.
The red shirts have accused the Election Commission of stalling over an investigation of alleged irregularities by the ruling Democrat party, concerning a multi-million dollar election campaign donation in 2005.
Thai authorities have also filed a court order to disperse the tens of thousands of protesters in the main shopping district.
The government intends to file another court order to arrest leaders of the rally, which it says violates Thailand's Internal Security Act imposed last month to maintain order during the protests.
The red shirts have hinted they may expand their rally to other areas of the city.