His letter was in response to The Times' leading article on September 20 in which it stated Thaksin's record "does not justify an illegal attempt to force him from power".

"The problem for 30 per cent of urban dwellers in Thailand who are mostly opposed to Mr Thaksin is that his political party, through what would appear to be traditional but illegal vote-buying practices, has cornered 70 per cent of the rural vote," Tonkin said.

The ex-ambassador, who was in Thailand from 1986 to 1989, asked: "As the declared purpose of the coup is to restore democratic rights and bring an end to corrupt domination of the rural vote, is action against tyranny and for democracy not fully justified?"

American authorities, meanwhile, were critical of the coup. US Secretary of State Condoleezza Rice said it was "a U-turn" and urged coup leaders to get the Kingdom on the right path "very, very quickly", Agence France-Presse reported from New York.

"The biggest problem is that in a Southeast Asia that was pretty stable ... it's a U-turn," she said in an interview on Monday with The Wall Street Journal.

The State Department on Monday urged the coup leaders to avoid politically motivated actions and called for elections to be held ahead of a one-year deadline set by the military junta.

The message came after the generals set up a high-powered committee to look into the books and tax records of the deposed PM, his cabinet members and their relatives, warning ill-gotten assets could be seized.

"Certainly, what we want to see happen as this process moves forward is a quick hand-over to civilian authorities and that any investigations or other activities that are done again be done in accordance with the law rather than being done for political purposes," State Department deputy spokesman Tom Casey said.

Washington has condemned the coup and is studying the possibility of reviewing military and other assistance to Thailand, a key Southeast Asian ally.