At a press conference to report police progress to mark the sixth month since the military junta seized power from the Thaksin government, police chief Seripisut Temeyavej said Surin had been summoned on Monday, after police concluded the investigation into alleged violation of the foreign business law.

He said Surin had already been informed of the police request and would come and testify on April 3.

Three other people were also accused of the same charge and will meet the police on March 27.

Seripisut said his officers will ask public prosecutors to file charges against Surin and three others within two months.

Kularb Kaew, which is majority-owned by Surin, is accused of acting as a nominee to acquire Shin Corp's shares on behalf of Temasek Holdings.

Surin had earlier insisted that he financed his investment in the company with his own money. Though Thai, he has developed a huge business in Malaysia - Multi-Purpose Holdings - of which he is the executive director.

He bought a 68-per-cent stake in the company for Bt2.7 billion.

However, despite his insistence, Thai authorities continued to investigate the nominee issue. The Commerce Ministry's report also concluded that Surin was a nominee on the grounds that the proceeds used to buy the stake came through a "mysterious channel".

The money was transferred from the Fairmont Investments Group, based in the tax-haven British Virgin Islands. Surin himself ordered the financial transaction on behalf of Greenland Co Ltd, which delegated power over Fairmont to Surin.

The identities of the shareholders of Fairmont and Greenland are unknown and Surin's investment automatically triggered questions about whether he was acting as Temasek's nominee.