Chuan, the former premier, now senior adviser to the opposition Democrat Party, said yesterday that if any head of government writes such a letter, the public should be informed, especially in a democratic country.

Chuan said the letter showed Thaksin acts against whatever democratic principles he claims to be standing for, and any such message could easily be conveyed via the US Ambassador in Bangkok without having to write directly to Bush.

Some believe the letter also contains a Thaksin lament that a "charismatic figure" with power beyond the constitution is trying to remove him from power.

The caretaker government has denied that the letter contains such a statement.

"I personally believe the intention of the letter is not to explain the [political] situation but to express [Thaksin's] views … It's not right. If any foreign state wants to know something, they can ask, but we should not voluntarily write to them to let them know how we are. Our country is not in an inferior position," Chuan said. The government had spokesmen to clarify such doubts, if there were any. He said it was like the government trying to say problems in the deep South were caused by the previous administration, which he [Chuan] headed.

"They can't cover it up," said Chuan, referring to the letter. "It's hard to keep a secret in the United States, and one day the letter will be revealed. It's better that [Thaksin] reveal it by himself rather than having a foreign state do it … Thais deserve to know the premier's view so they can see if it fits the reality or not."

Meanwhile, outgoing senator Kraisak Choonhavan said that Thaksin's secretary Prommin Lertsuridej's comment that Bush wrote a reply on July 3 - but the contents could not be revealed - only added to an already suspicious situation. He blamed Thaksin for creating the political mess.