Supporters of Thailand's embattled premier camped out in Bangkok for a second day on Monday, police said, as a blockade of Bangkok's airports by rival anti-government protesters entered a seventh day.

About 15 000 red-shirted pro-government activists had converged on city hall in downtown Bangkok on Sunday night, and around 1500 of them remained there on Monday morning, police said.

Their presence had raised fears that further bloodshed could stain Thailand's bitter political crisis, with clashes between the two camps in a northern city last week leaving one person dead.

"We will rally again this afternoon at the same place. Right now we are allowing our people to rest," Chinawat Haboonpard, a leader of the pro-government group, told AFP.

He said the group had not yet decided whether to launch a blockade of the Constitutional Court, which is due on Tuesday to wrap up a case that could see the ruling party disbanded for fraud.

The verdict could see Prime Minister Somchai Wongsawat and other leaders banned from politics.

"It's not yet concluded whether we will go to the Constitutional Court on Tuesday. We have to consult among ourselves for the best solution," he said.

There were no reports of clashes between the group and their yellow-shirted foes in the People's Alliance for Democracy, the group which has occupied both of Bangkok's airports since last week in its bid to topple the government.

The PAD says it will not leave the terminals until Somchai resigns, alleging that his elected government is a corrupt proxy for exiled former premier Thaksin Shinawatra, who was ousted in a coup in 2006.

Many of the pro-government protesters outside city hall wore headbands reading "Thaksin" — a sign of the influence the tycoon still wields despite living abroad to avoid a jail sentence for corruption.

Thaksin and his allies draw huge electoral support from Thailand's largely rural northern poor, while the Pad is backed by the Bangkok business elite and middle classes, along with elements in the military and the palace.

AFP