The first group of firms suspected of financing red shirts protests reported Monday to Department of Special Investigation (DSI).
Family members of former PM Thaksin Shinawatra including his ex-wife Khunying Pojaman Pombejra and his children are scheduled to turn themselves in Tuesday.
Representatives of eight companies from an overall 83 individuals and firms were scheduled to report for questioning by eight sets of teams comprising officials from DSI, the Anti-Money Laundering Office, the Office of the Narcotics Control Board and the Revenue Department.
Representatives of listed company SC Asset Corp. owned by Thaksin's family was the first company appearing at the DSI head office Monday to be questioned seeking more information on the case by officials.
DSI director general Tharit Pengdit said the companies in question will be given more time to prepare relevant documents and clarifications before investigators.
The investigators later decided to allow the eight firms to clarify their financial transactions to the officials July 19.
On Tuesday, five more companies and Thaksin's family members are scheduled to report to the investigators.
The army chief earlier signed a summons for 83 persons and companies whose accounts have been frozen on suspicion of financing the Red Shirt
protests to report to the Department of Special Investigation (DSI) from June 28-July 31.
Among the 83 individuals and companies are 23 family members of fugitive ousted prime minister Thaksin, 23 politicians, 15 businesspersons, 17 protest leaders from the United Front for Democracy against Dictatorship (UDD), and five retired senior military and police officers.
Meanwhile, Deputy Prime Minister Suthep Thaugsuban, as director of the Centre for the Resolution of the Emergency Situation (CRES), said Monday that the investigation of alleged unusual transactions is not intimidation, but is aimed at preventing instigation in future.
Suthep also ignored the threat of reds leader Somyot Preuksakasemsuk to file a complaint against CRES for freezing the accounts, in which he said affects the work of the persons alleged to have supplied funds to the anti-government cause.
The centre director said the CRES reaction will cut the flow of money used to finance moves to incite disruptions in the country, adding that the CRES process is done step by step, beginning with observing the unusually active accounts of some 100 persons and firms, but some were removed from the CRES monitoring list after scrutiny of nine months of transactions and finding no link to the movement.
Suthep said the remaining 83 individuals and companies will be studied to determine whether they have financially supported the ill-intentioned groups and if any involvement is found, they will face legal action.