Bangkok  - Thai authorities on Saturday prepared to rid Bangkok's two airports of anti-government protestors who have cut off the capital's passenger air traffic, stranding an estimated 100,000 plane passengers and losing the nation millions of dollars daily.

Prime Minister Somchai Wongsawat on Thursday declared both Suvarnabhumi International Airport and Don Mueang, Bangkok's old international airport, under emergency decree and ordered the police, air force and navy to clear the facilities of thousands of followers of the People's Alliance for Democracy (PAD), a movement that has been staging increasingly violent protests in Bangkok for the past six months to bring down the government.

To pave the way for a crackdown, Somchai on Friday sacked the national police commissioner, General Phatcharawat Wongsuwan, who has been lenient with the PAD in the past and is blamed for allowing them to seize the capital's airports. Suvarabhumi has been closed to air traffic since Wednesday and Don Mueang since Thursday.

The PAD has attracted a diverse base of backers from Bangkok's middle class, provincial people opposed to corruption and the country's political elite.

The police have been reluctant to attack the demonstrators, who include many middle-aged women, families with young children, hard-core golf-club-wielding guards and veteran political agitators.

Metropolitan Police Chief Suchart Muankaew has promised to first attempt to negotiate with the PAD leaders to make them leave the airports before applying force.

PAD leader Sondhi Limthongkul on Friday flatly rejected negotiations.

The last time the police cracked down on the PAD, at a demonstration outside Parliament on October 7, two protestors were killed when tear-gas canisters were fired into the crowds.

The police came under public criticism for the action, and Queen Sirikit, the wife of Thailand's revered King Bhumibol Adulyadej, attended the funeral of one of the victims.

But the PAD's seizure of Bangkok's airports has turned many former sympathizers against them.

The closures have stranded an estimated 100,000 passengers who want to leave the kingdom, according to Tourism Minister Weerasak Kowsurat. Industry sources said they are losing 3 billion baht (86 million dollars) a day in unshipped cargo.

Governments around the world have warned their citizens against travel to Thailand, hitting the country's tourism sector, which has already been hit by the global financial crisis, and the United States has criticized the PAD.

"While we respect the right to freedom of expression, seizing an airport is not an appropriate means of protest," the State Department's acting deputy spokesman Gordon Duguid said in a statement.

The airport crisis has demonstrated the weakness of the current government. Somchai has essentially moved his cabinet to Chiang Mai, 550 kilometres north of Bangkok, for fear of a coup.

Somchai is the brother-in-law of Thaksin Shinawatra, a former prime minister who was ousted by a bloodless military coup in September 2006 and is now living in self-imposed exile, a fugitive from the law after being sentenced to two years in jail on an abuse-of-power charge.

However, Thaksin remains a key character in Thailand's unfolding political drama. He has threatened to return soon to politics despite his fugitive status, and observers said they suspect the growing political chaos would set the stage for his comeback.

The PAD's main mission is to block the return to power of Thaksin and the kind of money-politics he represented.

The group is known to be seeking a military coup to launch their proposed "new politics," which would favour appointee governments over elected ones.

But if the military stages a croup this time, it was expected to face immediate opposition from the "Red Shirts," a pro-government group that has rivalled the PAD in leading civil unrest.

"They will fight back right after the coup, starting in Bangkok, so they will have to kill a lot of people," said Chaturon Chaisaeng, the former leader of Thaksin's now defunct Thai Rak Thai party who has close ties with the current government.

Although the military's last coup toppled Thaksin from power in a bloodless putsch, it ultimately failed to stop his followers from returning to power in the December 2007 general elections.

The current government is led by the People Power Party, which came to power on a pro-Thaksin platform. (dpa)