Wittaya Nithitham, chief of the AMLO’s legal division, said the agency had also frozen an additional Bt90 million belonging to the consortium as authorities pursued legal actions against NVPSKG, which earlier received a multibillion-baht compensation pay-out from the government.

The Criminal Court ruled late last year that the consortium had conspired with senior government officials in an action that caused major damage to the state as the faulty design and implementation of the massive waste-water treatment facility in Samut Prakan province meant it could not be used upon completion.

Prior to the court’s ruling, the consortium had received the first instalment of the compensation money – Bt3 billion- from the government, which lost an arbitration case and was ordered by the Supreme Administrative Court to pay the private firms.

The second instalment of the compensation pay-out, of more than Bt4.7 billion, plus another US$32 million (Bt1.1 billion), were due to be paid earlier this year but the AMLO intervened and asked the government to suspend the payment.

Now the DSI, as requested by Pol Maj-General Chaiya Siri-amphunkul, the AMLO chief, will pursue criminal charges against the consortium.

The investigation is due to be completed by the end of this month while another team of investigators will pursue civil liability charges against the consortium.

The consortium’s member companies are among Thailand’s major construction firms and are backed by former politicians who conspired with senior bureaucrats and abused the system resulting in huge damage to the public.

The AMLO chief said the agency would attempt to recover more funds and return the money to the state while the private firms might appeal the agency’s decision.