Thailand is sinking deeper into crisis. Anti-government protesters have shut down the capital's two airports, threatening to turn the political stalemate into an economic crisis.

Voxant Newsroom/AFP

ALMOST 300 weary Australian travellers are on their way home from Thailand on the first of a series of evacuation flights organised by Qantas.

The airline on Tuesday said 289 passengers, mostly Australians and British Airways ticket-holders, had boarded a Qantas flight from Phuket to Singapore at 3.39am local time (7.39am AEDT).

The Qantas passengers are among thousands of travellers who have been caught up in anti-government protests in Bangkok, where the People's Alliance for Democracy (PAD) has blockaded the city's two main airports.

The flight left the Thai holiday island one-and-half hours after its scheduled departure, because each passenger had to be manually processed, a Qantas spokeswoman said.

The passengers touched down in Singapore at 6.20am local time (9.20am AEDT), where they will be accommodated on existing flights back to Australia on Tuesday.

"Depending on what the passenger requirements are, where they want to go, we'll accommodate them on all flights accordingly," the Qantas spokeswoman told AAP.

"That aircraft that is operating that charter service, will turn into Qantas flight 72 to Perth, but it won't necessarily be carrying any passengers unless there were passengers on that flight that wanted to go to Perth."

It has been a long run home for the Australian travellers, who on Monday had to endure a 14-hour bus trip from Bangkok.

Qantas will run another relief flight out of Phuket at 2am local time (6am AEDT) on Wednesday, part of an effort by airlines to boost services from alternative airports to clear the thousands of passengers stuck in Bangkok.

Qantas chief executive Alan Joyce has said the airline will consider adding more flights out of Phuket, if required.

Meanwhile, Singapore Airlines has organised twice-daily flights from U-Tapao, a military airport 200km from Bangkok, to Singapore.

Earlier, Australians stuck in Bangkok were warned not to run up expenses in the hope it will be covered under travel insurance.

Consumer group Choice said many insurers do not cover for cases of civil unrest.

"It really is a question of who you are covered with and the profile of the incident concerned," spokesman Christopher Zinn told ABC radio.

One insurer that has agreed to help its customers is Medibank Private.

The company says it will pay even though cases of civil unrest are not covered in the policy.

"While the cover currently does exclude benefits in circumstances such as those in Thailand... this is not the time to be quibbling over fine print," Medibank Private spokesman Craig Bosworth told ABC Radio.