"At the time I was accompanying Khun Thaksin to see Mr Koizumi [the Japanese premier]. In an official vehicle, Khun Thaksin picked up his mobile phone and told the person on the other end to buy some shares for him. I was shocked," said the senior diplomat, who retired from the Foreign Ministry last September.

Kasit, also a former ambassador to the United States, revealed that Thaksin had acted undiplomatically in dealing with the Malaysian premier, Abdullah Ahmad Badawi, at the height of the violence in southern Thailand.

"When Khun Thaksin went to the United Nations to attend a

joint UN-Asean session [last year], he did not behave properly when addressing the session, which

was co-chaired by the UN secretary-general and the Malaysian premier. In his address Thaksin did not mention the name of the Malaysian premier," said Kasit.

In another incident, the former envoy said Thaksin had refused to see Abdullah when the latter requested a meeting.

Overall, Kasit said Thaksin's handling of his Malaysian counterpart had damaged the relationship between the two leaders.

On violence in southern Thailand, Prasong Soonsiri, a former foreign minister, said he believed Thaksin's mismanagement had contributed significantly to the worsening of the situation.

"Such mismanagement stemmed from his failure to use solid intelligence for decision making. Instead, Thaksin turned to one of his former classmates, the deputy Army chief in the South, for information which was similar to what he wanted to hear," said Prasong.

Asda Jayanama, another former ambassador to Washington, said the former diplomats felt they should tell the public the truth about the Thaksin regime during this crucial time.