Britain, France, Sweden and Austria are warning expats in Thailand and citizens visiting the country to stay away from political protests in Bangkok as they could turn more violent.

Britain warned its nationals against all but essential travel to the Thai capital due to the 'increasingly volatile' situation on the streets. 'This advice reflects our concern for the safety of British nationals planning to travel to Bangkok, given the risk that violence could break out without warning during the increasingly volatile political crisis,' the Foreign Office said.

'The situation is changing on a daily basis, and we recommend that British nationals living in Thailand or travelling to the country check the travel advice on the Foreign Office website regularly for details of further developments,' it continued.

French foreign ministry spokesman Bernard Valero said in a statement: 'We advise our compatriots to exercise the utmost caution and in particular not to go to places where there are political gatherings.'

He expressed concern over stern warnings by Thai army spokesman Sunsern Kaewkumnerd that force could be used in a crackdown against anti-government protestors in Bangkok.

'We reiterate our call to the authorities and protestors to act responsibly. It is more indispensable than ever for dialogue to prevail over confrontation,' he added.

The Swedish foreign ministry is warning against any 'unnecessary travel' to Bangkok. Austria's foreign ministry also issued a warning, advising against any unnecessary trip to the Thai capital, citing a 'high security risk for the greater Bangkok area'.

But the warnings do not apply to people in transit going through the airports in Bangkok. The Thai authorities have stressed that both Suvarnabhumi and Don Mueang airports are operating normally.

They latest advice comes after more have died in recent days in the ongoing political unrest. A series of grenade blasts ripped through a pro-government rally in Bangkok leaving three dead and 70 injured, including foreigners, in the latest bloodshed in the heart of the Thai capital.

The authorities said five grenades were fired from within the anti-government Red Shirt protesters' sprawling encampment, which has been fortified in recent days with sharpened bamboo stakes and piles of car tyres.

The Royal Thai Government said that it attaches priority to ensuring public safety, including that of foreigners residing in Thailand, and will continue to implement measures to ensure public safety, including checkpoints and patrols.