U.S. Commerce Secretary Wilbur Ross has divested his interests in oil tanker company Diamond S Shipping and is in the process of selling off his holdings in another shipping firm, Navigator Holdings, a Trump administration official said on Tuesday.

Ross had originally intended to retain his shipping interests following his confirmation in February. But the 79-year-old investor came under criticism after disclosures on Sunday that one of Navigator's major clients is the Russian gas company Sibur, a firm whose owners include members of Russian President Vladimir Putin's inner circle.

Information about the business ties between Navigator, which operates gas-carrying ships, and Sibur was based on leaked documents from offshore law firm Appleby that are part of the so-called Paradise Papers, which show details of business dealings by wealthy people and institutions ranging from Ross to Britain's Queen Elizabeth and trading firm Glencore.

Reuters has not independently verified the documents.

"He began divesting his Navigator interests in May," the administration official said of Ross. "He is nearing completion of that process."