Read our travel guidance: is Bangkok safe?

Tourists in Thailand have been put on alert for possible violence as a British man was slightly injured in a bomb blast in Bangkok today amid the country's deepening political crisis.

The man, aged 28, was walking near to the home of Prem Tinsulanonda, a former prime minister, in the popular old district of the capital when the explosion took place at around 2pm local time (0700 GMT).

The bomb exploded hours after Foreign Office updated its travel advice to Britons visiting Thailand. The advice says: "There is a high threat from terrorism throughout Thailand. Attacks could be indiscriminate and against places frequented by foreigners.

"Opponents of the Prime Minister have called a demonstration to march from Sanam Luang to Government house in Bangkok on the morning of 14 March 2006. Further demonstrations are expected to continue during the coming weeks. You should avoid large crowds and public gatherings, as there is a risk of public disorder."

Police in Bangkok said that the device had been hidden beneath a stone bench near to an unoccupied security booth. Three cars parked nearby were damaged by the blast.

The attack has been blamed on protestors linked to political instability caused by a campaign to oust Thaksin Shinawatra, the Prime Minister. He has responded to the dissent by calling snap elections on April 2.

Gamol Santiglanhul, a police colonel, was quoted by Reuters as telling a Bangkok radio station: "It was primarily meant as a threat or to cause havoc to keep the political turmoil going. Coincidentally, the security guards just happened to be inside the house with Papa Prem."

The Canadian embassy said that an earlier report of one of its nationals had also been wounded was a mistake by a hospital. The man entered the hospital at the same time as the British tourist.

The Prime Minister denounced the attack on a visit to the Chantaburi province: "We can’t yield to bandits," he said.

Kongsak Wantana, the Interior Minister, told reporters that witnesses had seen a man in his 20s planting the bomb, which appeared to be similar to devices that went off near the Justice Ministry in January and at the Interior Ministry the previous month.

Since the anti-Thaksin campaign started in September, there have been several small bomb blasts in Bangkok, but most of the others went off during the night and nobody was hurt.

A small bomb exploded at a Buddhist meditation centre associated with a key Thaksin critic last month.

Prem, who was inside the house when the bomb exploded, served as prime minister for eight years in the 1980s. The 85-year-old retired general chairs the 18-member privy council and is the chief adviser to King Bhumibol Adulyadej.

"He just wondered why a bomb was put in front of his house," Thammarak Isarangura, the Thai Defence Minister, told reporters.

Anti-Thaksin protesters have vowed to step up their campaign next week, raising fears of violence and army intervention in a country with a long history of military coups.

A Foreign Office spokeswoman said: "It was a small bomb. Two people were injured, and one was a British man. He was taken to hospital for treatment to minor injuries."

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