The U.N.’s top official for human rights lambasted Western right-wing politicians like Donald Trump and Nigel Farage in a speech Monday, describing them as “populists, demagogues and political fantasists.”

In an extraordinary attack made during a security conference at the Hague, Zeid Ra’ad al-Hussein compared their rhetoric to that of the Islamic State of Iraq and Greater Syria (ISIS) extremist group.

“Populists use half-truths and oversimplification — the two scalpels of the arch propagandist,” the U.N. High Commissioner for Human Rights said. “The Internet and social media are a perfect rail for them, by reducing thought into the smallest packages: sound-bites, tweets.”

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While al-Hussein mentioned Trump and Farage, along with leaders like Hungary’s Prime Minister Viktor Orban, Czech President Milos Zeman, Austrian politician Norbert Hofer, Slovak Prime Minister Robert Fico and French nationalist politician Marine Le Pen, the main target of his speech was Dutch anti-immigration politician Geert Wilders.

“What Mr. Wilders shares in common with Mr. Trump, Mr. Orban, Mr. Zeman, Mr. Hofer, Mr. Fico, Madame Le Pen, Mr. Farage, he also shares with Da’esh,” he said, using the Arabic language acronym for ISIS.

Wilders, who is facing criminal charges for inciting racial hatred, said in a recently released campaign manifesto that he would close all mosques and ban immigrants from Muslim countries if elected. His party, the Freedom Party, currently leads opinion polls in the Netherlands ahead of next year’s election.

Wilders also addressed this year’s Republican National Convention in Cleveland, where Trump officially accepted the party’s nomination for President.

Describing the Dutch leader’s manifesto as “grotesque,” al-Hussein said that “history has taught Mr. Wilders and his ilk how effectively xenophobia and bigotry can be weaponized.”