Hungarian Prime Minister Viktor Orban accused George Soros, the Jewish billionaire philanthropist who survived Nazi persecution, of fomenting anti-Semitism by helping immigrants come to Europe, MTI state news service reported.

Soros and his Open Society Foundations, which funds dozens of NGOs in Hungary, “bear responsibility for the increase in anti-Semitism in Europe,” Orban said in a letter to Ronald S. Lauder, the president of the World Jewish Congress, MTI reported Friday. Soros, 87, who eventually emigrated to the U.S. after World War II, said last year that Orban used Nazi-era propaganda methods to try to discredit him in a national billboard campaign.

Orban has built a border fence to keep immigrants out in a vow to protect Hungary from people he’s called “Muslim invaders.” In the letter, he said immigrants to Europe included those whose “political and religious views markedly increased the sense of insecurity in Jewish communities.”

Orban won a fourth term as prime minister last month and has become a ringleader for anti-immigrant populist forces in Europe. Open Society Foundations said this week that it was moving its staff from Budapest to Berlin, citing a government crackdown on NGOs.