A group of journalists behind the Panama Papers offshore accounts expose published an investigation Wednesday detailing how a distant relative of Russian President Vladimir Putin has made a fortune.

The Organized Crime and Corruption Reporting Project published a piece claiming that Mikhail Shelomov, the son of Putin's cousin, has over the years amassed nearly $600 million in assets.

Investigative journalists have written about Putin's childhood friends and distant relatives amassing fortunes before. Putin has denied helping his entourage to get rich.

Wednesday's piece detailed how Shelomov's company amassed stakes in lucrative businesses run by Putin's inner circle.

The OCCRP was one of the media outlets that brought to life documents of a Panamanian law firm showing how hundreds of rich and powerful people registered companies in tax havens.

Russia's Novaya Gazeta newspaper published a piece this summer about Shelomov, whom it described as a mid-level clerk in a shipping company.

In an interview with the newspaper, Shelomov confirmed that Accept, a company registered in his name, owns a broad range of assets including a share in Bank Rossii, which is co-owned d by Putin's childhood friends. He refused to comment on a suggestion that his company was a front for somebody else.