(Adds details of subpoenas, background on loans,)
FRANKFURT/WASHINGTON, Dec 5 (Reuters) - A U.S. federal investigator probing alleged Russian interference in the 2016 U.S. presidential election asked Deutsche Bank for data on accounts held by President Donald Trump and his family, a person close to the matter said on Tuesday.
Germany's largest bank received a subpoena from Special Counsel Robert 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 organization hundreds of millions of dollars for real estate ventures, said it would not comment on any of its clients.
Mueller is investigating alleged Russian attempts to influence the election, and potential collusion by Trump aides. Russia has denied U.S. intelligence agencies' conclusion that it meddled in the campaign and Trump has said there was no collusion with Moscow.
The German bank is one of the few major lenders that has lent large amounts to Trump in the past decade. A string of bankruptcies at his hotel and casino businesses during the 1990s made most of Wall Street wary of extending him credit.
A U.S. official with knowledge of Mueller's probe said one reason for the subpoenas was to find out whether Deutsche Bank may have sold some of Trumps mortgage or other loans to Russian state development bank VEB or other Russian banks that now are under U.S. and European Union sanctions.
Holding such debt, particularly if some of it was or is coming due, could potentially give Russian banks some leverage over Trump, especially if they are state-owned, said a second U.S. official familiar with Russian intelligence methods.
One obvious question is why Trump and those around him expressed interest in improving relations with Russia as a top foreign policy priority, and whether or not any personal considerations played any part in that, the second official said, speaking on the condition of anonymity.
During his White House campaign, Trump said he would seek to improve ties with Russian President Vladimir Putin, which had been frequently strained during President Barack Obama's administration.
There was no immediate response to the Deutsche Bank subpoena from Trump's lawyers.
The subpoena was earlier reported by German daily Handelsblatt.
FINANCES A RED LINE
In a July 9 interview with the New York Times, Trump said Mueller should not extend his investigation into Trump's finances if they were not directly related to the Russia accusations.
Asked if delving into his and his family's finances unrelated to the Russia probe would cross a red line, Trump replied, "I would say yeah. I would say yes."
The president declined to say what he would do if Mueller began such an examination, but he continued, I think thats a violation. Look, this is about Russia.
Trump had liabilities of at least $130 million to Deutsche Bank Trust Company Americas, a unit of the German bank, according to a federal financial disclosure form released in June by the U.S. Office of Government Ethics.
The Deutsche debts include a loan exceeding $50 million for the Old Post Office, a historic property he redeveloped in downtown Washington, mortgages worth more than $55 million on a golf course in Florida, and a $25 million-plus loan on a Trump hotel and condominium in Chicago, the disclosure shows.
All of those loans were taken out in 2012 and will mature in 2023 and 2024, according to the disclosure.
Deutsche Bank rejected demands in June by U.S. House Democrats to provide details of Trump's finances, citing privacy laws.
Internal Deutsche Bank documents seen by Reuters feature the names of Trump's former campaign manager Paul Manafort and his wife, Kathleen, in a series of client profiles.
Deutsche declined to confirm if the Manaforts were clients or if it had received a subpoena from Mueller for information on them.
Lawyers for Manafort did not immediately respond to a request for comment.
In October, Manafort pleaded not guilty to charges including conspiracy to launder money and conspiracy against the United States. The charges were brought as part of Mueller's investigation.
In January, Deutsche Bank agreed to pay $630 million in fines for organizing $10 billion in sham trades that could have been used to launder money out of Russia. (Reporting by Arno Schuetze and Tom Bergin in Frankfurt, and Nathan Layne, John Walcott, Karen Freifeld and Jonathan Landay in Washington; Writing by Alistair Bell; Editing by Keith Weir, Mark Potter and Frances Kerry)