Britons should avoid all but "essential" travel to Bangkok, the Government warned today.
The Foreign Office has changed its travel advice relating to the Thai capital because of fears over the safety of British nationals, given the risk "that violence could break out without warning".
It follows a series of explosions today near a massive encampment of anti-government protesters in Sala Daeng in Bangkok's business district. The blasts left dozens of people injured.
In a statement, the Foreign Office said: "At 15.45 today, the Foreign Office amended its travel advice to advise against all but essential travel to Bangkok.
"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 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."
The updated travel advice on the Foreign Office website states: "We advise against all but essential travel to the city of Bangkok, in light of ongoing political demonstrations and outbreaks of violence within the city.
"This advice does not apply to passengers transiting Bangkok Airport on their way to other destinations in Thailand or internationally."
It goes on to say that Britons "should exercise extreme caution throughout the country" and avoid demonstrations and large gatherings.
It adds: "The political situation in Thailand is volatile and tense. Violence could break out without warning."
The department is not currently advising against travel to other parts of Thailand, apart from the southern provinces of Pattani, Yala, Narathiwat and parts of Songkhla, where it advises against all travel.
Thailand has seen growing tensions between red-shirted anti-government protesters and security forces, often ending in violent skirmishes. Earlier this month, 25 people were killed during clashes.