"The SEC board has done its best in every case, including Thai Beverage Plc's listing application and issues involving Shin Corp. There is no policy to replace it," he said.

Thanong said all directors were experienced, talented and honest, particularly SEC secretary-general Thirachai Phuvanatnaranubala. All have served honestly and based their decisions on the legal framework of the country.

"There are no irregularities in SEC operations. Everybody abides by the law. We also have former Finance permanent secretary Panas Simasathien on the board. This ensures transparency and a determination not to cause any damage to the SEC," the minister said.

Since Singapore's investment arm, Temasek Holdings, completed its takeover of Shin Corp in January, the SEC has been accused of acting in favour of the buyer. Immediately after the takeover announcement, the SEC was criticised for permitting Temasek to be omitted from making tender offers for other listed companies owned by Shin Corp, such as CS Loxinfo, ITV Plc and Shin Satellite Plc.

Temasek was also allowed to quote a below-market price for a tender offer of shares from Advanced Info Service Plc shareholders.

The SEC also came under fire for the soft action taken against caretaker Prime Minister Thaksin Shinawatra's children, who breached securities laws.

And the SEC also found itself accused of indecisiveness in Thai Beverage's listing application. The whisky distiller and beer brewer later decided to seek a dual listing on the Singapore Exchange and the Stock Exchange of Thailand.

"Every issue is explainable. Anyone who has doubts or evidence of any irregularity should come forward," said Thanong.