President Donald Trump is “the worst perpetrator of false information” in the United States, according to the U.N. Special Rapporteur on Freedom of Expression and Opinion.

David Kaye, a law professor tasked by the United Nations with researching freedom of expression and online content regulation in at least six countries, told Digital Rights Monitor in an interview published Thursday that governments are often responsible for widespread disinformation — and the United States is no exception.

“Governments are real offenders when it comes to disinformation,” Kaye said. “You know, governments are putting out false information. I mean, in my own country, the United States, the worst perpetrator of false information is the President of the United States.”

It’s a sharp rebuke to Trump, who often weaponizes the phrase “fake news” to immediately dismiss any criticism of him from the press.

“I hope everyone, even the Fake News Media, is having a great Christmas! Our Country is doing very well,” the president tweeted, for example, on Christmas.

Politifact, which tracks politicians’ truthfulness, lists the majority of Trump’s political assertions as false. Trump received widespread condemnation this year for his hysterical response to a group of migrants and asylum seekers traveling from Central America to the American border, where some of them — including children — were tear-gassed. Trump insisted that the caravan was made up of “criminals and unknown Middle Easterners,” a claim that is not backed up by any facts.