Thailand's ex-prime minister Yingluck Shinawatra has been taken by leaders of the country's military coup, along with some family members and politicians.
Yingluck was kept for several hours and then driven to an undisclosed location, the BBC reported.
Six senior military officers have been put in charge of government departments, with provincial commanders stationed at local government buildings. Major news networks, including the BBC and CNN, have been shut off.
Thai protesters gathered during an anti-coup protest despite the martial law
Yingluck, along with acting Prime Minister Niwatthamrong Boonsongphaisan, had been ordered to report to the military headquarters, as well as more than 100 other politicians.
Robert Amsterdam, counsel to former Thai Prime Minister Thaksin Shinawatra who is the brother of Yingluck, said active consideration is being given to the formation of a government-in-exile.
“The military coup carried out by the Army of Thailand does not have any legitimacy nor does the Army of Thailand have a mandate from the people of Thailand to govern the country," he said in a statement.
"Given the Army of Thailand’s human rights record, we are extremely concerned for the safety of the political detainees, and we urge the international community to remain on high alert.”
Amsterdam alleged that a number of foreign governments have already expressed their willingness to host such a government-in-exile.
Foreign Secretary William Hague said he was "extremely concerned" at the situation. "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."
Hundreds of British tourists in Thailand will have to observe a strict night curfew following the military takeover there.
Around 800,000 Britons visit the country every year and those there at the moment will need to be indoors between 10pm and 5am under the terms laid down in Thursday's bloodless coup. The main tourist areas are still considered safe.
The advice added: "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."