"I don't have the details but this is not a practice to be encouraged," Annan told CNN television on the sidelines of the UN General Assembly meeting.

"We as an organisation have always supported governmental changes through democratic means, through the ballot box. As the African Union, for example, has indicated they do not support those who come to power through the barrel of a gun."

Annan urged the Thai people to "remain calm." He told CNN, "Over the past decade or so they have established a solid democracy and institutions under the leadership of the king. And I'm sure they will be able to restore that institution and go back to a democratic system as soon as possible."

Thaksin is in New York for the assembly and has cancelled plans to give a speech to the meeting after the military staged a coup and ousted him. Thaksin, who had been due to speak today, initially switched places with Montenegro on the speaker's list to allow him to speak yesterday evening due to the takeover.

But just three hours before he was expected to address the 192nation world body, UN deputy spokeswoman Marie Okabe announced that ``Thailand is no longer on the General Assembly speaker's list this evening.'' She gave no explanation for the cancellation.

Meanwhile the United States said it was monitoring the situation with concerns and is uneasy about the military takeover in Thailand.

The US State Department said in its statement issued on Tuesday that it hoped the political differences in Thailand can be resolved through democratic principles. There have been no indications of violence, but "we are monitoring the situation with concern." The department described the situation was still unfolding.

"We continue to hope that the Thai people will resolve their political differences in accord with democratic principles and the rule of law," the statement said.

The State Department responded initially with caution but injected an expression of concern several hours later in its second statement of the day.

In New York, US Secretary of State Condoleezza Rice returned to her hotel from UN headquarters to speak with her staff about the coup. US Ambassador John Bolton said it was still too early to comment but appealed for the maintenance of the rule of law.

"We have press reports and I think for now the important thing is to look for the sustaining of constitutional processes in Thailand," Bolton said.

Agencies