Cambodian Prime Minister Hun Sen called a rival "crazy and stupid" over his attempts to get Facebook to release details of the way the Southeast Asian country's ruler has used social media.
- Mr Rainsy says Hun Sen used Facebook to commit human rights abuses
- A 29-year-old was arrested for calling the government "authoritarian" on Facebook
- Mr Rainsy has been in exile since being charged with defamation in 2015
Former opposition leader Sam Rainsy's legal team filed the lawsuit in California last week, saying that Hun Sen was using the platform to commit human rights abuses and deceive the electorate.
Among other allegations was that Hun Sen was paying for false Facebook "likes" to mislead voters about his support.
"This person is crazy and stupid," Hun Sen told thousands of university graduates in the capital Phnom Penh, saying Mr Rainsy was just jealous because his official Facebook page had 4.5 million "likes" compared to the Prime Minister's 9.4 million.
In an interview with ABC, Mr Rainsy said Facebook could clear his name by revealing the accusations of buying likes were true.
"It's a fake popularity," he said accusing the leader of buying millions of likes from click farms. "Then he pretends to be very popular and he uses this as a basis to crack down on the population."
Mr Rainsy said Hun Sen uses Facebook likes to claim he represents the people, accusing Facebook of being involved in "tricks" that allow him to cling on to power.
Hun Sen said he had no idea who had liked his own page.
Arrested over Facebook post
The case has drawn attention to the central role of Facebook in political discussion in Cambodia, where the government has shut down the main opposition party, arrested its leader and cracked down on media and civil rights groups over the past year.
A 29-year-old man was ordered to pre-trial detention on Monday over comments posted on Facebook, which included calling the government "authoritarian". He was arrested last week on his wedding day.
Sam Rainsy's petition against Facebook said the platform had been used by the Government to make death threats and alleged that state money had been spent in advertising on Facebook, where Hun Sen's backers have built a strong presence.
Facebook's public relations department did not respond to requests for comment on the case.
Cambodia will hold elections in July, but opposition parties have been crushed in the lead up.
Mr Rainsy said without help from the Australian government, there is "very little chance of free and fair elections".
"We really expect Australia to help restore the democratic process and ensure the holding of a free and fair election in July," he said.
"Australia could help a lot because we look up to Australia as a model of democracy in the region."
Mr Rainsy lives in France, where he fled in 2015 after a conviction for defamation that he says was politically motivated.
He recently resigned as leader of the Cambodia National Rescue Party, a move he said was made to save the opposition group.
"After my resignation my party was still dissolved and my successor Mr Kem Sokha has been arrested and put in jail," he said.
Mr Sokha is currently on trial for treason.