Prime Minister Somchai Wongsawat declared a state of emergency around the capital's two main airports, which would allow security forces to oust thousands of anti-government protesters from the terminals.

Somchai accused the protesters of "holding the country hostage and the public hostage."

"I do not have any intention to hurt any members of the public," he added, though the imposition of the measures raised the possibility that violent clashes could break out as authorities moved on Suvarnabhumi international airport and the city's older, smaller Don Muang airport.

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The declaration empowers the government to suspend some civil liberties, including restricting the movement of people and prohibiting mass assembly in certain locations.

The People's Alliance for Democracy, which has been demanding the resignation of Somchai and his government, seized control of Suvarnabhumi international airport on Tuesday, forcing the cancellation of all flights in and out of the capital and sending thousands of tourists to hole up in Bangkok hotels.

The standoff, which began three months ago when the group occupied the prime minister's office compound, has paralyzed the government, battered the stock market, spooked foreign investors and dealt a serious blow to the tourism industry.

Government Spokesman Nattawut Sai-kua earlier called the seizure of the airports "a terrorist act."

"The prime minister says we have to use peaceful means," he said. "(Security officials) will negotiate (with protesters) first and we will go step by step, adhering to international standard and the law."

The protesters are seeking the resignation of Somchai, whom they accuse of being a proxy for former Prime Minister Thaksin Shinawatra. Thaksin, who is Somchai's brother-in-law, is in exile, a fugitive from a conviction for violating a conflict of interest law.