Michael Cohen, U.S. President Donald Trump's personal attorney, walks to the Loews Regency hotel on Park Ave on April 13, 2018 in New York City.

Michael Avenatti, the lawyer for porn star Stormy Daniels, said Tuesday that President Donald Trump's personal attorney Michael Cohen, within three months after the 2016 presidential election, received about $500,000 from a company controlled by a Russian oligarch who since has been interviewed by special counsel Robert Mueller's team.

Avenatti also suggested in a Twitter post that "these monies may have reimbursed the" $130,000 payment that Cohen made to Daniels right before that election.

NBC News reported that it had reviewed financial documents that appear to support Avenatti's account of the transactions.

The money, Avenatti claimed, came from billionaire Russian businessman Viktor Vekselberg, who has ties to Russian leader Vladimir Putin.

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"Mr. Trump and Mr. Cohen have a lot of explaining to do," Daniels' lawyer said in a tweet.

A report prepared by Avenatti's law firm notes that Cohen has claimed that the source of the money initially paid Daniels was from a home equity line Cohen tapped on October 26, 2016.

"However, as detailed below, within approximately 75 days of the payment to Ms. Clifford, Mr. Viktor Vekselberg, a Russian Oligarch with close ties to Russian President Vladimir Putin, caused substantial funds to be deposited into the bank account from which Mr. Cohen made the payment," the report claims.

"It appears that these funds may have replenished the account following the payment to Ms. Clifford."

The report goes on to say that Vekselberg and his cousin "routed eight payments to Mr. Cohen through a company named Columbus Nova LLC ... beginning in January 2017 and continuing until at least August 2017," the report said.