US Commerce Secretary Wilbur Ross has been accused by the New York Times of retaining a business relationship with a Russian oligarch under US sanctions and a son-in-law of Russian President Vladimir Putin.

The revelations came during a leak of financial documents at the weekend.

The ties were disclosed in the so-called “Paradise Papers,” a mass of documents leaked to German newspaper Suddeutsche Zeitung and reported Sunday.

The millions of documents mostly originate from a Bermuda-based legal services provider that works on offshore investments.

Reports on Sunday suggested that Ross did not disclose an interest in a shipping company called Navigator Holdings, a company that transports gas for Russian company SIBUR.

The main shareholders of Sibur are Putin’s longtime friend, billionaire Gennady Timchenko and Kirill Shamalov.

Ross, however, has since denied that he didn’t disclose these holdings.

In an earlier statement on Monday from the Department of Commerce it was further claimed that the holdings are openly listed in a form on the Office of Government Ethics website.

The commerce secretary added that there was nothing improper about Navigator Holdings relationship with SIBUR.

“A company not under sanction is just like any other company, period.”

It was a normal commercial relationship and one that I had nothing to do with the creation of, and do not know the shareholders who were apparently sanctioned at some later point in time.”