Thai Prime Minister Thaksin Shinawtara, currently in New York, declared a state of emergency on Tuesday night as troops seized key locations in this capital and took control of the state-run television.
Thaksin, who is attending the annual UN General Assembly session, called on the military to respect the authority of his deputy prime minister Chitchai Wanathasin, after he sacked Army Commander-in-Chief General Sonthi Boonyaratkalin, believed to be the prime mover behind the coup.
Thaksin's broadcast was cut off in mid-sentence. It has been common in past military coups — Thailand has experienced 19 since 1932 — for the military to seize control of the airwaves as their first step to seizing power.
Shortly after Thaksin's broadcast was cut, a message appeared on public TV from the Reform Group for Democracy said the army was in full control of the armed forces and police without facing any opposition.
Panitan Wattanayagorn, a political science professor at Chulalongkorn University who specialises in military affairs, said the coup seemed to be the work of General Sonthi. Whether the coup leaders will meet resistance is still unclear.
"There is a faction within the military loyal to Thaksin and another one loyal to now former Army Commander-in-Chief Sonthi," said Panitan.
He said it remained to be seen whether there would be a confrontation between the military factions.
"Overall, the trend is not positive, to have the military getting involved in politics, but if they can prevent violence and hold a general election, things might be back to normal in a few weeks," Panitan said.
Witnesses reported seeing tanks on the streets of the capital and parked on the Royal Grounds near the Grand Palace.
Thaksin, a billionaire telecommunications tycoon who has been prime minister since 2001, has been abroad since Sep 9 on state visits to Finland, Cuba and the US to attend conferences but many suspect he is away to avoid a brewing political crisis at home.
In New York, UN security officials said Thaksin had not yet entered the UN buildings.
The Thai delegation had requested to allow Thaksin to speak on Tuesday evening, according to Marie Okabe, a UN spokesperson.
The premier has been under pressure to resign since January, when his family sold its share in the Thaksin-founded Shin Corp to Singapore's Temasek Holding in a tax-free deal that irked Bangkok's tax-paying middle classes and elite.
Thaksin dissolved parliament in February and called for a snap election in an effort to regain his legitimacy in the face of mounting street protests against his allegedly corrupt administration and dictatorial leadership.
Thailand's three main opposition parties boycotted the April 2 polls, which Thakin's Thai Rak Thai Party won.
The results, however, were annulled by the constitutional court in May after Thailand's much revered King Bhumibol Adulyadej said he had found the election undemocratic and urged the judiciary to act.
Thaksin's political fortunes have arguably been on the decline since.