"The SEC has put the Shinawatra family's interests before the national interest," Sirichok said.

"We are gathering more information to prove that the entire process involves something more significant than a mere wrong tick [on a form]. Rather, it is an effort to disguise asset concealment."

At a press conference, the securities watchdog cleared Thaksin and his daughter Pinthongta of violating securities laws, but said his son Panthongtae failed to comply with disclosure rules and takeover codes.

Panthongtae could face a fine of more than Bt50 million for three offences, but not a jail term.

SEC secretary-general Thira-chai Phuvanat-naranubala insisted that jail terms are imposed only for violations of Articles 246 and 246 of the Securities and Exchange Act, and serious offences like insider-trading and accounting fraud.

Only seven offenders out of 72 violation cases had been jailed, he said.

The SEC also said that there is only one Ample Rich. Custodians and brokers - mainly Nava Vickers Ballas Securities (Thailand) and UBS's Singapore branch - had accidentally filed inaccurate reports, which sparked speculation that there were two firms named Ample Rich involved in Shin-share transactions.

Democrat MP Korn Chatikavanij said yesterday's press conference would not be the last the SEC held on the controversial transactions.

"It's insulting to the public," he said. "How does the SEC know that UBS simply received the shares [as a custodian] when the company said in an acquisition form that after receiving the 10 million shares from Nava, its total holding in Shin would be 15 million shares?"

The Democrats will submit a list of issues that remain unclear to the SEC.

Sirichok said that the explanation concerning UBS's role was vague, noting that the acquisition report was signed by an executive director of the world-class financial institution.

"All along, ticking the wrong box has been used as an excuse, including this time. To whom did the other five million shares belong then? This is actually an off-market transaction. Why didn't the SEC investigate this issue?" he asked.

Another issue lies in the address of Ample Rich - Matterson Trust Co (BVI) Ltd. Sirichok doubted if Matterson owned Ample Rich and this is part of the asset-concealment allegation. He also pressed the SEC to reveal the identity of Matterson's beneficial owners.

Thirachai said that the SEC could do nothing when brokers or custodians made reporting errors.

"If they ticked the wrong box, what could we do? By the way, changing custodians is not wrong as it depends on the share owners' choices. Particularly, the transactions affect nobody as they did not lead to a change in the company's share price," he said.

Thirachai also made it clear that the SEC's probe focused solely on the paper trail. It did not follow the money trail.

The question of whether any payments for the shares were made on each transaction was left to other state agencies, which still doubt any illegal transactions were made.

Although the case involves several offshore entities, the Bank of Thailand and the Anti-Money Laundering Office have shown no interest in following the money trail.

Remarkably, in 1992, when several major stock investors - including Song Watcharasriroj - were charged with manipulating share prices, the SEC flexed all its muscles to trace all paper and money transactions that could lead to accomplices so that it could establish an ironclad case.

Without evidence of payments being made, people involved in the Shin transactions are entitled to the benefit of the doubt.