Germany’s largest bank received a subpoena from Mueller several weeks ago to provide information on certain money and credit transactions, the person added, confirming a report by German daily Handelsblatt published on Tuesday.
Deutsche Bank, which has loaned the Trump organization millions of dollars for real estate ventures, said it would not comment on any of its clients.
Deutsche Bank rejected demands in June by U.S. House Democrats to provide details of Trump’s finances, citing privacy laws.
Mueller is investigating alleged Russian attempts to influence the 2016 U.S. presidential election and potential collusion by Trump aides.
Russia has denied meddling in the election and Trump has said there was no collusion.