He did so after receiving a ringing endorsement from the country's revered king and as ousted Prime Minister Thaksin Shinawatra flew into London for a "private" visit.

"In order to create peace in the country, the king appoints General Sondhi Boonyaratkalin as head of the Council of Administrative Reform," said the announcement on state-run television.

"All people should remain peaceful, and civil servants should listen to orders from General Sondhi Boonyaratkalin from now on."

Sondhi, 59, who is close to Thailand's constitutional monarch, is a Muslim in a Buddhist-dominated nation. He led a precision takeover overnight without firing a shot, sending soldiers and tanks to major intersections and around government buildings.

This came as the popularly elected Thaksin - accused of corruption and undermining democratic institutions - was in New York for the opening of the United Nations General Assembly.

Asked if there would be moves to confiscate Thaksin's vast assets, Sondhi said at a news conference that "those who have committed wrongdoings have to be prosecuted according to the law."

Sondhi did not elaborate, but an announcement later on state-run television said the newly formed Council of Administrative Reform had sacked the state audit commissioners and given more powers to Auditor General Jaruvan Maintaka to investigative government corruption, which could lead to a confiscation of Thaksin assets.

Sondhi said he would act as prime minister for two weeks until a new leader is found, that an interim constitution would be drafted within that time, and that Thailand's foreign policy and international agreements will not change.

There would be a general election in October 2007, he said.

Sondhi said the coup - Thailand's first in 15 years - was necessary to end government corruption, insults to King Bhumibol Adulyadej, and what the general called Thaksin's attempts to destroy democratic institutions.

About 500 people gathered outside army headquarters lending moral support to the military and chanting "Thaksin Get Out!"

Nearly 20 tanks - their gun barrels festooned with ribbons in the monarch's color, yellow - had blocked off the Royal Palace, Royal Plaza, army headquarters and Thaksin's office at Government House.

The overthrow was needed "to resolve the conflict and bring back normalcy and harmony among people," Sondhi said on nationwide TV.

Meanwhile, the newly formed Council of Administrative Reform put the country under martial law and declared a provisional authority loyal to the king, seizing television and radio stations and ordering government offices, banks, schools and the stock market to close for the day.

And a statement from the coup leaders urged workers and farmers - Thaksin's key constituents - to remain calm. It warned that unauthorized gatherings of more than five people were punishable by six months in prison under martial law.

The Nation newspaper said several senior government officials and others close to Thaksin had been arrested. They included Deputy Prime Minister Chitchai Wannasathit and Thaksin's top aide, Prommin Lertsuridej.

Agriculture Minister Sudarat Keyuraphan, one of Thaksin's closest political associates, fled to Paris with her family, it added.

Central bank head Pridiyathorn Devakula said the public had accepted the coup, so it was unlikely to have much impact on foreign confidence in the country, and that the Thai baht had recovered from its overnight low with no intervention.

In New York, a Thai business executive who said he was speaking on behalf of Thaksin said the toppled leader was not resigned to his fate.

"The prime minister has not given up his power," said Tom Kruesopon, chief executive of Boon Rawd Trading International, who said he was traveling with Thaksin.

But Thaksin's official government spokesman, Surapong Suebwonglee, also traveling with him, was gloomier. "We have to accept what happened," he said. "We are not coming back soon."

ASSOCIATED PRESS More reports: A20-A21