WASHINGTON — Commerce Secretary Wilbur Ross faces questions about his financial disclosures to Congress and the government after a report that he has business ties to the son-in-law of Russian President Vladimir Putin and an oligarch under U.S. sanctions.

Sen. Richard Blumenthal, D-Conn., called on the Commerce Department’s inspector general to open an investigation into the matter, which concerns Ross’s ownership stake in a shipping company that did business with a Russian firm.

“In concealing his interest in these shipping companies – and his ongoing financial relationship with Russian oligarchs – Secretary Ross misled me, the Senate Commerce Committee, and the American people,” Blumenthal said in a statement. “Secretary Ross’ financial disclosures are like a Russian nesting doll, with blatant conflicts of interest carefully hidden within seemingly innocuous holding companies.”

Ross isn’t alleged to have broken any law and may not have even violated federal guidelines for ethics disclosures.

The Commerce Department said in an unattributed statement on Sunday that Ross was unaware who owned the Russian firm and has never met the owners, and that he has recused himself from transoceanic shipping matters.

“Secretary Ross works closely with Commerce Department ethics officials to ensure the highest ethical standards, and is committed to restoring our economy and creating American jobs,” the department said.

On Sunday, multiple media organizations including the New York Times published reports based on documents leaked from the Bermuda law firm Appleby to the German newspaper Suddeutsche Zeitung that were shared with the International Consortium of Investigative Journalists in Washington. The ICIJ has termed the leak the Paradise Papers because of its similarity to the “Panama Papers” leak in 2016, from the Panamanian law firm Mossack Fonseca, for which the organization won a Pulitzer Prize.

The Appleby documents included details of Ross’s stake in a shipping company, Navigator Holdings, according to the Times. Ross said in the government ethics disclosure he filed following his nomination that he held an investment in the company worth as much as $10 million. Ross’s overall holdings are estimated at $3 billion, according to the Bloomberg Billionaires Index.

What Ross didn’t disclose is that the company’s clients include a Russian energy company called Sibur, whose owners include Putin’s son-in-law and a Russian oligarch close to the Kremlin who has been sanctioned by the U.S. government, according to the Times. That information was revealed in the Appleby documents, the paper said.

Sibur was Navigator’s fifth largest customer in 2016, accounting for nearly 8 percent of its revenue, according to Securities and Exchange Commission filings. Mitsubishi Corp. is its largest client, according to data compiled by Bloomberg, accounting for just over 16 percent of revenue.

There is no requirement for executive branch nominees to disclose clients or customers of a business in which they are shareholders. The disclosure requirement applies only to direct payments related to a nominee.

Walter Shaub, who was the director of the Office of Government Ethics at the time Ross filed his disclosure, signed off on the document. Shaub has since resigned and become a public critic of the Trump administration and its ethics practices.

The ICIJ hasn’t made the documents publicly available. Shaub didn’t return messages on Sunday. The White House didn’t respond to inquiries.

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(Sahil Kapur, Margaret Talev, Andrew Mayeda and David Carey contributed to this report.)