Former opposition leader Sam Rainsy has filed a landmark lawsuit against Facebook, seeking to force it to provide information about the account of Prime Minister Hun Sen at a time when the social media giant’s role in the political process has increasingly been called into question.

The application, a request for permission to serve Facebook with a subpoena for discovery, claims that Hun Sen has violated multiple Facebook policies, including buying “likes” and making death threats.

“There is significant evidence that Hun and his agents have systematically misused Facebook’s platform in violation of its policies, principles, and community standards,” the document reads.

The application, the first of its kind, claims the information sought in the lawsuit filed on Thursday will aid Rainsy’s legal defence in Cambodia, where he has been convicted of defamation for accusing the premier of buying Facebook likes.

The document refers to a 2016 article by The Post, which revealed that many of the premier’s Facebook likes were coming from outside the country, with sharp spikes occurring in countries like India, where he gained more than 250,000 in one month. “Mr. Sam’s federal Petition seeks information in Facebook’s possession regarding Hun Sen’s misuse of social media to deceive Cambodia’s electorate and to commit human rights abuses,” an accompanying press release said.

Rainsy fled the country in 2015 amid a slew of politically tinged convictions, many of them for defamation, and his former party was forcibly dissolved last year to widespread international outcry.Government spokesman Phay Siphan said the lawsuit amounted to “harassment” and that Rainsy was a has-been.

“I don’t make any mention of Sam Rainsy,” he said.

Rainsy’s lawsuit asks Facebook for information including the amount of “state money” spent to advertise on the platform. The application claims that according to Hun Sen’s “own communications”, his administration spends as much as $15,000 a day in generating fake likes and advertising.

It also accuses Hun Sen of using Facebook to make death threats against Rainsy and others, stating that “these activities violate Facebook’s policies and terms of use”. “We are counting on Facebook to help shed light on the regime’s manipulation of technology,” Rainsy said in the statement. “The Cambodian people and international community deserve the truth.”

“The issues raised in the lawsuit ask fundamental questions about Facebook’s role in the democratic process, including how it will react when being misused by repressive regimes,” said J Noah Hagey, Rainsy’s attorney.

Representatives from Facebook did not respond to requests for comment.

Facebook has come under fire for its role in spreading fake news, amplifying authoritarian government propaganda and sidelining independent voices with its new “Explore” feed. Cambodia was one of a handful of countries selected for the Explore field “experiment”, whereby official pages were relegated to a separate section of the News Feed, unless they paid a fee.

“Facebook were contacted in 2016 and made aware that Hun Sen was buying likes to give a false impression of his popularity and that this could influence the next election,” said Richard Rogers, one of Rainsy’s legal representatives with Gobal Diligence law firm.

“Hun’s account(s) remain active, and he continues to misuse Facebook in a manner which overtly violates Facebook’s formal Policies,” the suit claims.