Washington (CNN) Maria Butina, the recently indicted Russian national accused of being an agent of Russia, told the Senate Intelligence Committee earlier this year that Russian billionaire Konstantin Nikolaev had backed her financially, a source familiar with her testimony told CNN.

Butina made international headlines last week when the Justice Department announced her arrest and a grand jury formally approved charges of conspiracy and acting as a foreign agent. The federal case has added to a growing picture of undisclosed foreign attempts to lobby in the US and alleged Russian influence in the political system.

Nikolaev's office told CNN in an email Monday that he did provide some funding to a pro-gun organization run by Butina called Right to Bear Arms, but has not been in touch with her since 2014.

"Mr. Nikolaev has had no contact with Ms. Butina or her organisation since 2014," his office said in a message in English. "He briefly provided some funding to the organisation from 2012 to 2014 specifically to support their efforts in Russia to raise public awareness around certain domestic issues. His interest and support were strictly limited to that effort, and he has provided no support of any kind to them since that time."

The Washington Post reported earlier than Nikolaev's office said the billionaire had been in touch with Butina, but not that Nikolaev had given her organization money.

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