Entertainer Harry Belafonte attacked conservative benefactors Charles and David Koch on Sunday, suggesting the brothers influence activists who “would belong to the Ku Klux Klan.”

At a church service he attended while campaigning for Democratic New York City mayoral candidate Bill de Blasio, Belafonte said the Tea-Party-supporting moguls are flooding the country with money. He suggested the brothers have also started to “buy their way in” to New York City politics, starting with the medical care system.

“Already we have lost 14 states in this union to the most corrupt group of citizens I’ve ever known,” the 87-year-old singer said, as quoted by the New York Post. “They make up the heart and the thinking in the minds of those who would belong to the Ku Klux Klan. They are white supremacists. They are men of evil. They have names.”

“The Koch brothers, that’s their name,” he added.

De Blasio didn’t address the remarks at the service, according to the Post, but conceded after being pressed by reporters that he disagreed with Belafonte’s “characterization” of the Kochs.

A spokesman for the Koch brothers told Politico that Belafonte’s comments were “false and reprehensible,” adding that they were “indicative of the type of hateful rhetoric that leads to the breakdown of a civil and respectful society.”

The Kochs’ ties to conservative groups run deep: a little-known group called Freedom Partners with strong connections to the brothers came forward in September as the source of nearly a quarter of a billion dollars given to conservative political groups in 2012. The Kochs also back Americans for Prosperity, which launched a campaign against a Republican lawmaker who expressed openness to expanding Medicaid in his state under the Affordable Care Act.