“A probe has recently revealed that the contract to construct the plant is against public order and is thus considered void under the Civil and Commercial codes,” Somnuek Siangkong, spokesman for the office, said yesterday.

If the court considers the new evidence as material, it might retract its order for the government to pay more than Bt9 billion to the NVPSKG consortium for cancelling the project.

This was a new, important piece of evidence, he said.

Since the probe results emerged, both the Finance Ministry and Pollution Control Department have asked public prosecutors to petition the Administrative Court.

In late 2014, the Supreme Administrative Court found in favour of NVPSKG. The court reasoned that even though the project was cancelled on suspicion of corruption, the joint venture had already completed most of the work.

The department complied with the ruling, paying Bt3.17 billion and US$21.71 million to NVPSKG last year.

More instalments will follow if the court order is not cancelled.

The department sued former deputy interior minister Vatana Asavahame and 18 other defendants including NVPSKG for alleged land and contract fraud.

The court ruled in favour of the PCD, sentencing Vatana and 10 executives of the firms to jail.

However, the Appeals Court dismissed the case, prompting the PCD to appeal to the Supreme Court.