AUTHORITIES have stepped up their investigation to determine whether Thai nationals have been involved in money laundering, tax evasion or other financial crimes in connection with the “Panama Papers”, a massive data leak that has hit dozens of celebrities and world leaders.

Prime Minister Prayut Chan-o-cha yesterday pledged to take legal action against wrongdoers while responsible agencies were waiting for official documents before they proceeded with legal action after the disclosure of an unconfirmed list of 21 Thai citizens implicated as using the Panama-based law firm Mossack Fonseca’s services to hide assets overseas.

The 21 people include businessmen, bankers and other well-known persons.

Prayut said Thai authorities would also follow up on possible foreign prosecutions against wrongdoers. “If there were really Thais who committed [financial crimes], they could be put in jail,” he said.

Deputy premier Prawit Wongsuwan said people implicated in the Panama Papers cases would have to clarify their positions with regard to possible wrongdoing.

Pisit Leelawachiropas, the Auditor General, said his agency would work with the Revenue Department to check the tax records of the 21 people who reportedly had used Mossack Fonseca’s services.

In addition, the Auditor General will work with the National Anti-Corruption Commission, Anti-Money Laundering Organisation and Bank of Thailand to examine the money trails revealed by the massive data leak.

However, Justice Minister Paiboon Koomchaya cautioned that there should not be a foregone conclusion that all clients of the Panama-based law firm had committed wrongdoing since authorities had to examine details of the transactions prior to making a judgement.

He said authorities in Thailand were waiting for official documentation.

“It’s also possible that some names on the list might have used the service for appropriate investment purposes,” he said.

According to the Revenue Department, assets from abroad are subject to tax when they are brought into the country. Offshore companies are therefore often used to hide assets from authorities with the help of specialist law firms and banks.

Banyong Pongpanich, chief executive officer of Kiatnakin Bank, wrote on his Facebook page that he was shocked to see his name featuring in the so-called Panama leaks since he had never used Mossack Fonseca’s services and never heard its name before the scandal.

According to his own preliminary assessment, Banyong said there were probably separate lists, including one with names of those accused of wrongdoing and another of people who used to be executives at Phatra Securities.

In 2003, Banyong said executives, including himself, conducted a management buy-out of a firm held by Merrill Lynch, but he insisted the deal had been transparent and announced to the public, so the executives had nothing to hide.

Banyong said he owned stock and had conducted many offshore transactions before but not committed any illegal acts.

Mossack Fonseca has many branches around the world, including one in Bangkok, which has been operational since 2000. The Thai unit, Mossack Fonseca & Co (Thailand) has a registered capital of Bt2 million with its local office situated on Rama IV Road.

The firm is 51 per cent Thai-owned and 49 per cent owned by foreigners based in the British Virgin Islands. Its 2014 accounts show a loss of Bt125,947.