Thai Prime Minister Abhisit Vejjajiva arrives for a parliamentary session in Bangkok on Wednesday. (Chaiwat Subprasom/Reuters)

Thailand's army will start cutting off supplies of food, water and electricity in an area of central Bangkok if anti-government activists don't clear out, Thai officials say.

Army spokesman Col. Sansern Kaewkamnerd said security forces would "not use force at this stage," but his wording left open the possibility of more violence in Thailand's two-month political standoff if the Red Shirt protesters refuse to disperse.

The protesters — who say Prime Minister Abhisit Vejjajiva's government is illegitimate — have been camped out in Bangkok since mid-March.

"This is a full-scale measure to limit the freedom of protesters and to close down the area 100 per cent, starting at midnight," Sansern said.

The measures would include cutting water, electricity and mobile phone signals to the protest zone and stopping bus, rail and boat services to the area, Sansern said, adding that authorities would also "seal off entrances to the area."

The announcement came a day after Abhisit warned protesters to move out by Wednesday or face consequences that could also effect residents who live nearby.

Security forces may "implement measures that will have an impact on people in the area, not only the demonstrators but also workers and residents," Abhisit said.

Jatuporn Prompan, one of the protest leaders, said the Red Shirts would not disperse, adding that the demonstrators had access to their own electricity generators and were not dependent on a public power source.

New demands

The protesters have been calling on Abhisit to resign and dissolve parliament. Abhisit recently agreed to an early election date, but protesters responded by demanding that both Abhisit and his deputy prime minister face criminal charges over a deadly crackdown on protesters by security forces.

Protesters sleep under makeshift tents in the Red Shirt camp early Wednesday. (Wally Santana/Associated Press)

"We will wait here. If we can't have justice, you can come take our lives away," said another protest leader, Nattawut Saikua.

Government spokesman Panitan Wattanayagorn said late Tuesday the prime minister had lost patience and was rescinding his compromise offer to hold early elections on Nov. 14 as part of a reconciliation plan.

"He said there will no longer be any more compromises or conditions," Panitan told The Associated Press.

"Their refusal to stop the protest meant that the conditions that were set are being cancelled, including the election date."

The Red Shirts include the rural and urban poor as well as pro-democracy advocates. Many are supporters of former prime minister Thaksin Shinawatra, a populist leader who was accused of corruption and abuse of power and ousted in a 2006 military coup.

The protesters have staged a number of dramatic protests, including tossing bags of donated blood at the prime minister's home and office and surrounding parliament. On several occasions, protesters have clashed with security forces.

At least 29 people have been killed and hundreds have been injured, the Thai Health Ministry said.

With files from The Associated Press