US Special Counsel Robert Mueller has asked Deutsche Bank for data on accounts held by President Donald Trump and his family, a person close to the matter says.
Mueller is investigating alleged Russian attempts to influence the 2016 US presidential election and potential collusion by Trump aides.
Germany's largest bank received a subpoena from Mueller several weeks ago to provide information on certain money and credit transactions, the person said, without giving details, adding key documents had been handed over in the meantime.
Deutsche Bank, which has loaned the Trump organisation hundreds of millions of dollars for real estate ventures, said it would not comment on any of its clients.
The bank rejected demands in June by US House Democrats to provide details of Trump's finances, citing privacy laws.