Thailand's army chief called on the Government to resign today as a blockade of Bangkok's international airport left thousands of foreign tourists stranded.

The People's Alliance for Democracy (PAD) stormed the Suvarnabhumi airport on Monday night to prevent Somchai Wongsawat, the Prime Minister, landing there on his way home from a summit in Peru. The group has already occupied Mr Wongsawat's central Bangkok offices since August and are in a final push to unseat him.

But although General Anupong Paojinda, the Army chief, told them to end their blockade today, he also called on the government to resign and call fresh elections as part of a four-point plan to end the crisis.

The powerful Army chief insisted, however, that he was not about to launch a coup. "If a coup could end all the troubles, I would do it," he told reporters. "It is not going to resolve anything."

General Paojinda said that the suggestion that the government should resign was made in crisis talks this afternoon with high-level government officials, academics, economists and security officials. "We are not pressuring the government," he said.

The Government quickly rejected the general's call. "The Prime Minister has said many times that he will not quit or dissolve Parliament because he has been democratically elected. That still stands," a government spokesman said.

Among the holidaymakers stranded at the Bangkok airport are thousands of Britons, although a spokesman for ABTA said that the exact number is unclear because many were backpackers and independent travelllers.

With all flights in and out of the Thai capital cancelled, stranded passengers were crowding the $4 billion terminal, a regional hub and the gateway for 40 million passengers a year.

Amid scenes of chaos, tourists camped on the airport floors complained that they had had nothing to eat or drink since the PAD invaded the complex. Today, the protesters took over the control tower and said airlines would have to ask permission from them to land.

Tourists complained that check-in and other staff had run away as soon as the demonstrators swarmed into the airport, and restaurants and shops had closed their doors.

William Wilson, an English apartment manager who lives in Brisbane, said no-one could tell him what he should do. "I should have stayed in bed," he said.

Roy Manning, an electronics engineer from Cambridge who had been waiting in the transit lounge since 10.45 last night said tempers were fraying as conditions at the airport deteriorated. "They threatened us they were turning the power off and said there would be no food," he said. "We still don't know how we're going to get home."

Dressed in yellow, the royal colour, the protesters were walking around distributing food, ham sandwiches and packets of rice - much to the passengers' bemusement.

Cheryl Turner, 63, of Scottsdale, Arizona, needed to get home to cook a Thanksgiving holiday feast for her family tomorrow. She had asked neighbors to pull a turkey from her freezer a day ahead of time. "My turkey is sitting in the sink at home," she said.

The airport takeover was one of the boldest gambles yet by the PAD in its campaign to topple Mr Somchai, whom it accuses of being the puppet of his brother-in-law and predecessor, the billionaire Thaksin Shinawatra.

The blockade is threatening the country's crucial tourist industry in the run-up to the busy Christmas season. Airlines including Singapore Airlines, Cathay Pacific and British Airways have cancelled their flights to Bangkok.

The PAD vowed to bring its campaign to a final showdown this week, and violence has spiked.

A gang of government supporters in the northern city of Chiang Mai today shot dead an anti-government activist after dragging him from his car.

Earlier a grenade was thrown at PAD members camped out at a separate domestic airport in Bangkok, injuring at least three people, police said. Running street clashes between supporters and opponents of the government last night included the first open use of firearms by the anti-government militants. Police said that 11 government supporters were injured, some with gunshot wounds.

Britain urged restraint. Bill Rammell, the Foreign Office Minister, said: "I am deeply concerned about the worsening unrest in Bangkok over the last 48 hours. We urge all sides to this political dispute to resolve their differences peacefully and legally, respecting Thailand’s democratic institutions."

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