The BBC's Jonathan Head describes the scene at the airport
Bangkok's Suvarnabhumi airport has witnessed chaotic scenes as thousands of tourists remain stranded by anti-government demonstrations.
Protesters from the People's Alliance for Democracy (PAD) have completely taken over the control tower and all other areas of the capital's airport.
All flights were cancelled and thousands of frustrated travellers were slowly being bussed to hotels.
The PAD seized the facility after a political campaign lasting months.
Thousands of yellow-shirted protesters have occupied the airport, staging a mass sit-in throughout the terminal and blocking the main access road outside.
The BBC's Jonathan Head says the mood of the protesters is upbeat and good-natured, with PAD supporters distributing food and drinking water to all those gathered.
No one is offering any kind of help. Everyone is basically saying, there's nothing we can do
British tourist Hannah Simons
Outside the terminal, however, thousands of angry and tired passengers were waiting in long lines to be bussed to hotels.
British tourist Hannah Simons told the BBC's Five Live that they were in a dirty, overpriced, out-of-town hotel and that no one was doing anything to help them.
"Instead of helping us - all the people, the tourists, who are stranded here - there is no one who is basically offering any kind of support or help. Everyone is basically saying, there's nothing we can do".
But by late afternoon, most of the 4,000 travellers - some of whom had camped out with no food or water since the night before - had left, a Thai official told AP news agency.
There is no sign of flights resuming any time soon from the airport, one of Asia's biggest hubs.
Earlier, Rachel Kite, one of the stranded tourists at the airport, told the BBC that many people had been waiting for up to 16 hours.
We sympathize with the passengers but this is a necessary move to save the nation
Sondhi Limthongkul PAD protest leader
"We've not been told anything by the airport authorities or by the poor staff of Thai airlines, who are completely overwhelmed," she said.
"All of the information has been coming from the internet and from the BBC and other cable news channels."
Ms Kite said she did not feel she was in danger but that people were becoming "more and more tense" as the noise from protesters increased.
She said people were getting tired and some families with young children were running out of formula and food for them.
"I think the authorities are doing the best they can but inevitably tensions start to rise," she added.
"I don't know what happened to my flight," said one mother.
"They won't talk to us. And I'm angry and sad, because I have two small children. They are sick, so we want to go home."
BANGKOK AIRPORT CLOSED
Thousands of PAD protesters storm the airport
Protesters seize the air traffic control tower and airport closed
At least 3,000 passengers stranded for several hours in terminal building
Latest reports say terminal has been cleared but protesters refusing to leave
The PAD says it will continue to occupy the airport, despite a call from army chief Anupong Paochinda to end the siege.
"We sympathize with the passengers but this is a necessary move to save the nation," top protest leader Sondhi Limthongkul said on a makeshift stage at the besieged airport amid resounding applause.
A court later issued an injunction telling the group to leave the airport, a gateway for nearly 15 million visitors to Thailand last year.
But PAD spokesman Suriyasai Katasila said the group would appeal the court order.
"We won't pull out. We won't leave if (PM Somchai Wongsawat) does not quit," he told reporters.
Domestic flights out of Bangkok's old Don Muang airport were also grounded, all but severing air access to the outside world.
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