The Ministry of Mines and Energy has accused a foreign environmental activist of defamation and is threatening to sue after he questioned how they could afford luxury cars on government salaries.

In a statement released on Thursday, the ministry says that Alejandro Gonzalez-Davidson of activist group Mother Nature Cambodia, which has pushed for the Stung Cheay Areng dam to be scrapped, accused ministry officials and Chinese dam builder Sinohydro of corruption.

“All accusations must be based on the law, which means that if there are documents, witnesses and real evidence, please file a complaint with the Anti-Corruption Unit to take legal action,” the statement says.

But the ministry also references a much-maligned article of the anti-corruption law that allows for corruption complainants to be prosecuted for defamation if their complaints “lead to useless inquiries”.

“The exaggerations and completely wrong accusations made by Alejandro Gonzales-Davidson are not based on his independence as the director of a non-governmental organisation and is misinformation to fool the public through unprofessional media that has affected individuals’ reputations and the state and could have legal [consequences].”

In a Radio Free Asia interview on Tuesday, Gonzales-Davidson addressed government claims that Mother Nature had paid off dam protesters by explaining that his activists were not paid at all: “Our policy is that we have no salary for our staff. It’s not like officials at the Ministry of Mines and Energy who get a salary of less than $400 but when I went to drink coffee near the ministry I saw their cars worth $200,000 or $300,000. Can we ask where they get the money to buy those cars?”

He also claimed that government officials were “colluding” with Sinohydro.

Yesterday, Gonzalez-Davidson said that he had merely “raised a question” and had not actually said that officials were committing corruption.

“Defamation charges they think will have an effect of scaring people … but it would basically backfire on them because it would make the Areng issue even higher up in terms of international attention and many more thousands of Cambodian activists would be happy to replace me and get involved,” he said.