The confrontation at Suvarnabhumi international airport, which came as police tried to prevent more protesters arriving, ended without violence.

The police have said they will continue trying to regain control of the sites.

But the protesters say they will not leave until PM Somchai Wongsawat resigns, which he has refused to do.

A state of emergency has been declared at both Suvarnabhumi and the smaller, domestic Don Mueang airport, which the anti-government People's Alliance for Democracy (PAD) have taken over.

In a televised address on Friday, Mr Somchai promised a peaceful end to the situation, saying the stand-offs with anti-government demonstrators would be resolved by negotiation.

However, protest leader Sondhi Limthongkul, told supporters he would not negotiate despite a personal plea from the prime minister to hold talks.

Police reinforcements have moved into position at the airports, where at least 2,000 protesters have dug in behind barricades and barbed wire.

Demotion

Thousands of travellers remain stranded in Bangkok as a result of the blockade, which officials say is costing the country's economy millions of dollars every day.

Airlines started flying passengers out of a naval airbase 150km (90 miles) from the city on Friday but reports suggested that confusion and delays continued.

On Friday, police ordered protesters occupying Bangkok's domestic Don Mueang airport to leave, as tensions mounted there over the continuing demonstrations.

It followed news of the demotion of the country's chief of police to what officials said was an "inactive post" in the prime minister's office.

No official reason was given for Gen Patcharawat Wongsuwanbut's demotion, but government spokesman Nattawut Saikuar suggested to Thai TV that it was in connection with the protest crisis.

Police have not yet moved to break up the protests but have said they are prepared to take "other steps" if negotiations fail.

Government spokesman Nattawut Sai-Kau said police had been instructed to "do whatever is necessary to open the airports on the basis of non-violence".

Meanwhile, the government said that Mr Somchai would remain in the northern city of Chiang Mai indefinitely for his own safety.

The BBC's Quentin Sommerville in Bangkok says that Mr Somchai has already lost the confidence of his army chief, Gen Anupong Paochinda, and rumours of a coup are circling in the capital.

Turmoil

Thailand has been in political turmoil since former Prime Minister Thaksin Shinawatra was ousted in a military coup in 2006.

The PAD - a loose alliance of royalists, businessmen and the urban middle class - claim that the government is corrupt and hostile to the monarchy.

They have occupied a government complex in Bangkok for months, and declared at the beginning of this week that they were embarking on the "final battle" of their campaign to unseat the government.

Correspondents say the airport protesters appear increasingly isolated and are losing the support of their traditional sympathisers, the business elite.

The airport closure will cost the country around $4bn (£2.6bn) in lost business and cause serious damage to its reputation as a tourist destination, something from which it will take the country years to recover, say analysts.

BBC