Allegations about the contract signed in 2004 are not new. Thailand's attorney general office had dropped the case for lack of evidence, but the National Anti-Corruption Commission can file complaints directly to the Supreme Court.

The case it filed Monday accuses the four officials and the former head of Bangkok's Fire Department of abuse of authority, price collusion and corruption over the contract. The Supreme Court is supposed to rule next month on whether to accept the case and proceed to trial.

The complaints over the firefighting vehicles names: Apirak, former Interior Minister Bhokin Bhalakula, former Deputy Interior Minister Pracha Maleenont, former Commerce Minister Wattana Muangsuk and former Bangkok fire chief Atilak Tanchukiat.