Riot police have fled a checkpoint near Bangkok's Suvarnabhumi international airport after coming under attack by several hundred anti-government protesters.

About 150 police at the checkpoint jumped into their vehicles and drove away when they saw a convoy of protesters speeding toward them. Protesters have occupied the airport since late Tuesday, forcing the halt of all flights and leaving British holidaymakers stranded.

The situation for hundreds of Britons trapped in the country worsened today with the announcement that the airport will remain closed until at least 6pm Monday.

Andy Cooper, director general of the Federation of Tour Operators, said the five or six hundred British tourists stranded in Thailand with tour operators were in a "wait and see situation". It is estimated there are hundreds more independent travellers also stuck in the country.

A spokesman for Abta, the travel association, said: "Hundreds of British tourists are over in Bangkok with our members. They are in a better position than people who travelled independently.

"The operators are keeping in contact with them, making sure they are in hotels, and in many cases paying their bills. They are being looked after."

He said people with bookings to fly out to Thailand were being dealt with on a "rolling basis" and could choose to delay their trip, go to an alternative destination or ask for their money back.

A spokeswoman for tour operator Kuoni said they had been looking after about 200 clients in Thailand.

The confrontation, severing the capital from civilian air traffic, has taken a heavy toll on Thailand's economy and reputation.

So far security forces have only issued a warning to the protesters to leave and refrained from using force. The protesters say they will not leave until the government of Prime Minister Somchai Wongsawat resigns.

But the government's patience is wearing thin.

"The police will issue another warning to protesters to leave the two airports. The language in the warning will be stronger than the first one," said a police spokesman, Major General Amnuay Nimmano.

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