The Assets Examination Committee (AEC) will open a new investigation to determine whether ousted premier Thaksin Shinawatra disposed of his Shin Corp shares before taking office in 2001 or made a "faux transfer" and retained ownership.

"If Thaksin made the faux transfer of shares, he will be penalised under Article 100 of the National Counter Corruption Commission Act," AEC spokesman Kaewsan Atibhodi said yesterday.

If convicted, Thaksin could face a jail term of up to 15 years, he said.

Kaewsan said he saw the new probe as a follow-up to the asset-concealment case in which Thaksin won an acquittal by just one vote in 2001.

The previous case was about stashing his wealth with nominees, while the new case will be about the false reporting of share ownership, as Thaksin might have been the true owner of those shares, he said.

Kaewsan was speaking at a seminar organised by the Thai Journalists Association to shed light on Thaksin's tax liabilities - and his family's - stemming from the sale of Shin Corp last year.

He outlined the saga of Thaksin's wealth dating back to 1992.

Thaksin's telecom giant became a listed company in 1992, prompting the ousted premier to allow half of the company's equity stakes to be traded on the stock market, with the other half held by him and his family. After Thaksin decided to seek the premiership in 2001, he was forced by the graft law to relinquish his shares and those of his wife. He accomplished this by moving the shares to his three children and several nominees.

In the first round of the court battle over alleged asset concealment, Thaksin won an acquittal to keep his premiership.  The high court did not address legal issues about possible criminal and graft violations in having nominees hold his shares.

Regarding the shares transfer to Ample Rich Investment, accounting for 11 per cent of Shin equity stakes, Thaksin argued he had transferred the company's ownership to his son and daughter, Panthongtae and Pinthongta.

The Securities and Exchange Commission accepted Thaksin's explanation without checking to verify whether Thaksin or his children had the say on the shares in question.

The AEC would seek to verify the true ownership, which other authorities had omitted to confirm.

Another seminar panellist, Thitiphan Chuaboonchai, said a Supreme Court verdict in 1997 set a clear precedent that Thaksin's two children were liable to pay capital gains tax from the Shin Corp sale linked to their investment firm and Singapore's Temasek Holdings.

Thitiphan, the dean of Chulalongkorn University's law faculty, said the high court ruled that Thai officials of overseas-registered companies were obliged to pay tax for any profitable deals done on the company's behalf - regardless of where the deals took place.

Panthongtae and Pinthongta claimed tax exemptions, arguing their deals with Ample Rich took place abroad. The investment firm sold the shares at Bt1 par value to the two, who resold them to Temasak at Bt49 on the tax-free stock market.