Russian billionaire Viktor Vekselberg acquired his wealth in the post-Soviet era’s oil and gas industry. (Alexander Ryumin/AP)

President Trump’s personal attorney, Michael Cohen, met at Trump Tower in New York days before the 2017 inauguration with a Russian billionaire who was sanctioned this year by the U.S. government.

The meeting between Cohen and Viktor Vekselberg, who made his fortune in the energy industry, was an impromptu session arranged by Vekselberg’s cousin, Andrew Intrater, a New York investment manager who was also in attendance, according to a person with knowledge of the encounter.

Among the topics the three men discussed was Vekselberg’s desire for better relations between the United States and Russia, the person said, who added that Vekselberg did not encounter Trump or any of his other advisers. The meeting was first reported by the New York Times.

Later that month, Cohen signed a lucrative consulting contract with Intrater’s investment firm, Columbus Nova. Company officials have said that Vekselberg, who is Columbus Nova’s biggest client, played no role in Cohen’s hiring.

The Jan. 9, 2017, sit-down adds to a lengthy list of contacts between Trump associates and Russians with Kremlin ties during the campaign and the presidential transition.

It happened just three days after the U.S. intelligence community released a public report concluding that Russian President Vladi­mir Putin had directed an effort to interfere in the 2016 campaign with the purpose of hurting Democratic candidate Hillary Clinton and boosting Trump.

About a week after the meeting, Cohen, Intrater and Vekselberg were together again at a dinner in Washington to celebrate Trump’s inauguration. Intrater had contributed $250,000 to support the festivities and invited Vekselberg as his guest.

Investigators for special counsel Robert S. Mueller III have sought information about the three men’s activities as part of their investigation into Russian interference in the 2016 election. Earlier this year, Vekselberg was stopped by agents when he flew into a New York-area airport, the Times has reported. Intrater has also been interviewed by the special counsel team, according to a person with knowledge of the situation who, like others, spoke on the condition of anonymity.

Separately, Cohen is under investigation by federal prosecutors in New York scrutinizing his business practices and his efforts to quash negative stories about Trump.

A spokesman for Vekselberg and Stephen Ryan, an attorney for Cohen, did not immediately respond to requests for comment.

Intrater declined to comment. He told the Times that had he “known in January 2017 that I was about to hire this high-profile guy who’d wind up in this big mess, I wouldn’t have introduced him to my biggest client, and wouldn’t have hired him at all.”

Intrater and Cohen first met by happenstance, according to a person familiar with their relationship. Intrater was having dinner at a Manhattan restaurant in the fall of 2016 with some friends when one of them pointed out that Cohen was also dining there. The friend introduced Cohen to Intrater, and the two stayed in touch.

The Trump Tower meeting several months later was brief and impromptu, the person said. Cohen and Intrater were discussing setting up a meeting and Intrater noted that he was with Vekselberg near Trump Tower and asked if they could come by.

At the time, there was already growing scrutiny of the relationship between Trump associates and Russia. During the campaign, Trump frequently said that he hoped to rebuild ties between the United States and Russia, even as the U.S. government concluded that Russia had orchestrated cyberhacks of Democrats.

Several days before the Cohen-Vekselberg meeting, The Washington Post had interviewed Cohen about allegations in a research dossier compiled by a former British intelligence officer on behalf of the Clinton campaign that concluded Trump had coordinated with the Russian influence campaign. The dossier alleged that Cohen was part of that effort, which he denied.

Vekselberg made billions in the post-Soviet era in the oil and gas industry. He and the company he founded, the Renova Group, were sanctioned in April by the Treasury Department after the poisoning of a former Russian spy in Britain that Western intelligence officials have blamed on Russia.

Carol D. Leonnig contributed to this report.