The Ministry for National Assembly-Senate Relations has called for legal action against a Facebook user who accused its head, Men Sam An, of having an affair with disgraced Education Ministry official Kry Seang Long.

In a press release on Wednesday, the ministry accused the social media figure Chham Chhany, who is believed to be living abroad, of defaming Sam An, a deputy prime minister, with the “unacceptable” post on June 26.

“The cabinet would like to appeal to authorities at all levels to take legal action to find out the identity of the account owner and punish him according to law,” the letter said.

In his post, which included a picture of Sam An, Chhany claimed to have insider information that Sam An and Long were lovers. He also made a joke about Long’s recent fall from grace.

The former senior Education Ministry official was demoted last week after it emerged he had been arrested for sexually assaulting an interpreter while at a conference in South Korea in May.

Chhany, who has more than 250,000 Facebook followers, is already facing another defamation suit brought by the prime minister’s son Hun Manet, who complained to the National Police after the netizen linked the Hun family to logging barons.

Yesterday, via Facebook, Chhany said he “did not care about their legal action”.