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House speaker Paul Ryan and UN ambassador Nikki Haley will be honored at a dinner tonight funded in part by a Soviet-born oligarch whose business associates are under US sanctions, and whose political donations have reportedly been examined by special counsel Robert Mueller.

Len Blavatnik’s foundation is named as the ”patron sponsor” of the conservative Hudson Institute think tank’s award gala in New York. Previous award recipients include Ronald Reagan, Henry Kissinger, and vice president Mike Pence.

Blavatnik, a US citizen raised in the Soviet Union who is in business with two US-sanctioned Russian oligarchs, has dramatically increased his political donations in recent years. Since 2015, he has given $7.6 million to Republicans, $1 million to president Donald Trump’s inauguration committee, and half a million to Democrats, Federal Election Committee filings show. In the years before then, he made relatively small, bipartisan donations.

He gave $50,000 to the Hudson Institute event. The only higher spending sponsors are three Hudson Institute trustees, and billionaire hedge funder Paul Singer.

Some see the institute’s acceptance of the funds as hypocritical. In the past, its own Kleptocracy Initiative has often sounded the alarm about the corrosive influence of Russian cash.

“This dinner is a great example of exactly how supposedly philanthropic activism is converted into political access,” says Ilya Zaslavskiy, a member of the Kleptocracy Initiative’s advisory council. “It’s hypocritical to on the one hand say they fight kleptocracy…and at the same time they accept this money.”

A Hudson Institute spokesperson said in a statement, “The Blavatnik Family Foundation bought a table to our annual gala. We are grateful for all those who are supporting Hudson’s work tonight.”

Ryan will no longer attend the dinner as he hosts the arrival ceremony for former president George H.W. Bush’s memorial in Washington, his spokesperson said.

Blavatnik was born and raised in the Soviet Union, but left to America aged 21 in 1978, where he became a US citizen. In the 1990s, he returned to Russia as a businessman. He swiftly became one of the richest of a generation of post-Soviet oligarchs, making a fortune in the country’s newly privatized oil sector and the notoriously bloody “aluminum wars.”

Blavatnik and his longtime business partner, US-sanctioned oligarch Viktor Vekselberg, own a large stake in aluminum giant Rusal, which is owned by fellow oligarch Oleg Deripaska. Deripaska and Rusal are also sanctioned by the US Treasury, which says the oligarch “does not separate himself from the Russian state.” Both Deripaska and Vekselberg have featured in the Mueller probe, with Vekselberg reportedly questioned by Mueller’s team earlier this year.

A spokesperson for Haley didn’t respond to an emailed request for comment on Monday.

Update (Dec. 3, 2:15pm ET): Blavatnik’s firm Access Industries said in a statement that Blavatnik’s political donations were “motivated only by a desire to further a pro-business, pro-Israel agenda,” and “are a matter of public record and comply with all legal requirements.”