Foreign Secretary William Hague has urged Thailand to set out a "quick timetable" to restore a democratically elected civilian government following the military takeover in the south east Asian country.
Hundreds of British tourists are having to adhere to a strict night curfew after the bloodless coup and Mr Hague said the Thai authorities should not to resort to violence amid fears of the reaction to the takeover.
He urged Britons in Thailand or thinking of travelling to the country to keep monitoring the Foreign Office's travel guidance for the region which will be updated as events progress.
Mr Hague said: "I am extremely concerned by today's coup. The UK urges the restoration of a civilian government that has been democratically elected, serves the interests of its people and fulfils its human rights obligations.
"We look therefore to the authorities to set out a quick clear timetable for elections to help re-establish the democratic framework of governance.
"There should never be recourse to violence: only by openly discussing the full range of issues can Thailand move forward and reach a more stable position.
"We are monitoring the situation on the ground very carefully. British nationals in Thailand or thinking of travelling to Thailand should monitor the FCO's travel advice, which will be continually updated as events develop."
Around 800,000 Britons visit Thailand every year and those there at the moment will need to be indoors between 10pm and 5am under the terms laid down in the coup.
The Foreign Office (FCO) updated its travel advice for Thailand today. It said there is an increased military presence in Bangkok and tourists should allow extra time for journeys.
It said the curfew would not apply to those travelling to or from Bangkok airport but said travellers should continue to monitor social media and local news for updates as a number of media outlets have been taken off air by the Royal Thai Army.
The advice went on: "There is a risk of a violent reaction to the Army's announcement. We recommend that you exercise extreme caution and remain alert to the situation. If you're in any doubt about your safety, stay in your accommodation.
"Political demonstrations continue in and around Bangkok and elsewhere in Thailand.
"There have been indiscriminate attacks involving weapons and explosives at protest sites and at protest marches, causing casualties and deaths. Attacks have taken place during the daytime and at night.
"Protest action has caused significant disruption to roads in affected areas, with knock-on effects across the city. The situation is unpredictable and further protests are expected."
The FCO said tourists "should take extra care and avoid all protest sites, political gatherings, demonstrations and marches".
At present, the FCO is advising against all but essential travel to the provinces of Pattani, Yala, Narathiwat and Songkhla on the Thai-Malaysia border, although this is due to the threat of extremists targeting Westerners.
The FCO advises against all travel to the Preah Vihear temple area and the Ta Krabey/Ta Moan temple area on the Thai-Cambodian border due to the presence of troops in the area and the risk of outbreaks of fighting, although this is in relation to an ongoing dispute with Cambodia.
UK travel organisation Abta is also closely following events. An Abta spokeswoman said: "Thailand has grown in popularity with Britons in recent years although this is one of the quieter times of the year for visitors from the UK.
"While backpackers often go to the capital Bangkok, package holidaymakers typically travel to the coastal resorts of Phuket, Phangnga and Krabi in the south. The demonstrations that have been going on have been aimed at the government."
The Tourism Authority of Thailand said: "Businesses and public services are adjusting their operating hours to comply with the curfew.
"All airports in Thailand remain open, and air passengers with arrival and departure flights scheduled during the curfew can travel to and from the airports at any time as usual.
"We are closely monitoring the situation, and will be providing more updates as soon as there are further developments."
Thailand has been in an almost constant state of political upheaval in recent years, with this being the 12th coup since the end of absolute monarchy in 1932.
The governmental ups and downs have had little or no effect on tourism from Britain, with the country providing good-value, sunshine holidays to those keen to get away from inclement British weather.