Governments around the world warned their citizens to avoid any "non-essential" travel to Thailand as anti-government protesters stormed Suvarnabhumi, the country's main international airport.

China, France, New Zealand, Singapore, Britain, the United States, the Philippines, Australia and Japan issued travel warnings and avised citizens to steer clear or to act with caution if already in Thailand.

"The Chinese Embassy advises that Chinese citizens planning to visit Thailand should postpone their plans," a travel advisory on the website of the Chinese Embassy in Bangkok said.

"Chinese citizens currently in Thailand should pay attention to their safety and stay away from areas of protest marches and demonstrations."

Japan's foreign ministry issued a similar advisory. "They should collect information on new developments and stay away from places where protesters demonstrate," it said. "Citizens are therefore urged to avoid the areas of demonstrations, and to exercise caution if within the vicinity of any demonstrations."

The United States warned its citizens to check with their airlines if they were due to fly into or out of Bangkok.

A statement on the Bangkok embassy website said US citizens should avoid potentially volatile situations.

"We wish to remind American citizens that even demonstrations intended to be peaceful can turn confrontational and possibly escalate into violence," it said.

In a statement posted on its website, France's foreign affairs ministry advised French people due to fly through Bangkok to make alternative arrangements.

The New Zealand foreign affairs ministry advised travelers stranded at Suvarnabhumi to stay with other tourists, remain close to information counters and follow instructions issued by local authorities.

Similarly, Singapore said citizens without "a pressing need to travel" were advised to postpone their trip.

Britain's foreign office issued an updated travel advisory telling Britons to keep abreast of a "very uncertain" political situation.

"If you plan to visit Thailand you should consider the present situation when making your decision," it said on its website. "You should exercise caution, avoiding any demonstrations or large gatherings of people. "There remains the possibility of further violence."

At least 3,000 travellers were stranded Tuesday night when protesters from the People's Action for Democracy (PAD) entered Suvarnabhumi International Airport.

PAD aims to overthrow Thailand's democratically-elected government, which it accuses of nepotism and corruption. Protesters are asking for the resignation of Thai Prime Minister Somchai Wongsawat, a brother-in-law of former premier Thaksin Shinawatra.

The latest saga is expected to impact on Thailand's tourism. Last year, there were 14.8 million travellers to Thailand, according to its tourism authority.