Zsuzsa Hegedűs, one of Orbán’s longest-serving advisers, has known the prime minister since 2002 and described her relations with him as friendly. But in her resignation letter – published by Hungarian news agency hvg.hu on Tuesday – she said she had grown increasingly uncomfortable with Orbán’s “illiberal turn” in recent years. Orban has made anti-immigration rhetoric a key part of his political platform since 2015 and often uses far-right language, but his speech on Saturday – in which he railed against “race mixing” – was extreme even by his standards. In the speech, Orbán said mixing between Europeans was acceptable, but Europeans mixing with non-Europeans created “mixed-race” people. “We are willing to mix with each other, but we don’t want to become a people of mixed race,” Orban said. He added that countries where this is considered acceptable “are no longer nations”. Hegedűs said she had long defended the prime minister against accusations of anti-Semitism, but believed his latest speech was indefensible. “I am truly sorry that such a disgraceful attitude has forced me to end our relationship,” he wrote. Orbán’s office published his response to Hegedűs in which he accepted her resignation but denied that he was racist. “You can’t be serious to accuse me of racism after 20 years of working together. You know better than anyone that in Hungary my government follows a policy of zero tolerance for both anti-Semitism and racism,” he wrote. Subscribe to First Edition, our free daily newsletter – every morning at 7am. BST Orbán’s speech, delivered at an event in Băile Tuşnad, Romania, where he traditionally gives an annual keynote address, sparked an immediate reaction inside and outside Hungary. Such criticism is nothing new, and Orbán thrives on portraying himself as a fighter against so-called political correctness and European liberal elites. But resignations on matters of principle from his inner circle are extremely rare and show that even in some parts of the right there is concern about how his rhetoric on race is evolving. Next week Orbán is due to travel to Dallas, where he will open CPAC Texas, a gathering of US conservatives. Orbán counts former US President Donald Trump among his many admirers on the American right.