Almost 40 flights have taken off from Bangkok’s stricken airport since last night - but the planes were forced to leave the city empty as stranded Britons remained trapped in Thailand.

The ghost flights took off six days after they were grounded by anti-government protestors, who have seized the Thai capital’s two main airports.

The royalist People’s Alliance for Democracy (PAD) seized Suvarnabhumi international airport, ordering 88 planes to remain on the tarmac as commercial air travel was halted in the city.

The first of those planes have been given permission to leave, but not to take any of the tourists back home.

A spokeswoman for Airports of Thailand said: "Thirty-seven aircraft have left Suvarnabhumi. International airlines will have to contact us to take those stranded aircraft out of Suvarnabhumi."

Some countries, including Australia, have chartered special flights to rescue their nationals, but the British government appears reluctant to intervene.

Bill Rammell, a Foreign Office minister, said: “The key issue is the fact the two airports in Bangkok are closed and therefore you’ve effectively got planes stacking up and not being able to get slots.”

Twelve planes belonging to foreign airlines are still stranded at Suvarnabhumi, as well as 29 from Thai Airways, 16 of Thai Airasia, 15 from Bangkok Airways, and 22 aircraft from other airlines.

A Foreign Office spokesman said that British Embassy staff were regularly visiting British nationals stuck in Bangkok and providing consular help, such as refreshing supplies of prescription medication.

He suggested that U-Tapao, a small military airport, might offer some respite as thousands of hot and weary tourists - desperate for a flight home - crowded into the airbase, 90 miles south of Bangkok.

It has a small terminal with one X-ray machine and two sets of wheeled air-steps. As tempers frayed and tourists began shouting and shoulder-charging the glass doors into the terminal, Anne Ryan and Andrew Carter, from London, waited for newly purchased seats on a flight out of Thailand.

Originally booked on Eva Air, they said they could not afford to wait indefinitely for a flight home. They said Eva Air had told them that December 11 was the first date that they could fly, and that this had to be confirmed. “We've got to get back,” Ms Ryan said. “There's life and work and animals waiting for us.”

The frustration of stranded tourists grew yesterday as thousands of PAD protestors held a rally pledging to lengthen the demonstration that has brought the region's busiest hub to a standstill.

The latest protests came after several grenade attacks against the fiercely royalist PAD, which injured as many as 52 people and raised fears of open violence in Thailand's worst political crisis in decades.

In one attack, a grenade was hurled into the Prime Minister's compound in central Bangkok, which has been held by the yellow-clad PAD since August. PAD militants have attacked police trying to order several thousand of them to leave Suvarnabhumi airport, chasing riot squad officers away from the terminal and letting air out of their vehicle tyres.

PAD guards, armed with staves and clubs, have blocked roads into Suvarnabhumi - Thailand's main airport - checking identification before allowing access. Egged on by speeches from its leaders, the group said that it would “fight to the death” before surrendering Suvarnabhumi. The Prime Minister, Somchai Wongsawat, the leader of the ruling People Power Party, has refused to step down as demanded by the PAD. He has instead moved the seat of government to the relative safety of the northern city of Chiang Mai, a stronghold of government support.

Panitan Wattanayagorn, a political scientist at Chulalongkorn University, said he believed the two sides were slowly moving from posturing and isolated acts of violence towards open confrontation. He said: “With everybody moving into tight corners, nobody knows what will happen.” Polls showed that 60 per cent of Thais did not support either side, he added.

With Bangkok's Suvarnabhumi and Don Muang airports at a standstill for more than five days, pressure is on the Government to find a solution, salvage Thailand's tourism industry and find a way to assist as many as 100,000 stranded tourists, including perhaps thousands of Britons, to return home.

Openly hinting that he fears a military coup, Mr Somchai is awaiting a Constitutional Court decision - perhaps as early as tomorrow - that may dissolve his party if it is found guilty of vote-buying charges. Dr Panitan said that the King's birthday speech scheduled for Thursday might also push either side into giving way.

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