Tanks are reported as "heading for central Bangkok", reports confirmed by journalists on the ground, as of 11:41am EDT. There is suspicion the military action is an attempted coup, either to restore democracy after elections earlier this year were annulled, or to overthrow the existing government, in an effort to establish a system the nature of which is not yet known.

Prime Minister Thaksin Shinawatra is currently in New York, attending the annual meeting of the UN General Assembly. He went on Thai television to declare a "severe state of emergency" as news broke of the tanks' entering the capital. He ordered the military not to "move illegally" against the government or commit any illegal acts against civilians.

The BBC reports "An army-owned TV station is showing images of the royal family and songs linked in the past with military coups." It is unclear what the motivation behind the footage might be, which side it is intended to represent and who might be responsible for airing it on state television.

CNN reports tanks are "moving in toward government buildings", and that the PM is under severe pressure to step down amid mounting allegations of corruption and abuse of power. After stopping a car allegedly armed to explode in late August, Thai authorities detained five army officers for alleged complicity in a plot to assassinate the prime minister.

Opponents accused the PM of staging the "plot" in order to raise his profile in public opinion and increase his chances for victory in the elections scheduled for October. He still reportedly enjoys support among the rural poor, though urban voters have tended to express dissatisfaction with what appears to be ineffective and corrupt rule.

Despite apparently impassioned efforts to stay in power, the billionaire politician had promised to step down in early April, shortly after calling a "snap election" in an effort to end the crisis over leadership. While his party has won two consecutive elections by landslides, the April election was dissolved after allegations the PM himself attempted to rig the vote count.

There are currently reports that tens of thousands of pro-democracy demonstrators might return to the streets to demand reform as the military takes control of the country. There have in the past been violent clashes between the military and pro-democracy demonstrators and there are fears a new confrontation could end in bloodshed.

By 12:00 noon, New York time, as reports of PM Shinawatra's absence emerge from the UN General Assembly, there was video footage clearly showing tanks surrounding the government headquarters in Bangkok. Reporters said soldiers were seen ordering police to lay down their arms and cede control of the capital to the military.

By 12:14 EDT, a statement had been broadcast, signed by the Thai military, saying the military was in control of the government headquarters and of the nation of Thailand. There had not, at that time, been an official statement from PM Shinawatra as to the fate of his government, though presumably the state of emergency would remain in place as the military took the reins of state power. [s]

• BBC: "Thailand calls state of emergency"
• BBC: "Thai arrests over Thaksin 'plot'"
• BBC: "Thai court rules election invalid"
• BBC: "Thai prime minister to step aside"