Britain's Financial Conduct Authority (FCA) has put Deutsche under so-called enhanced supervision since the autumn, the source said.

The bank's London branch was fined 4.7 million pounds by the FCA in August for incorrectly reporting 29 million transactions between November 2007 and April 2013.

Enhanced supervision procedures are normally kept private and can follow fines.

The Times newspaper first reported the increased supervision.

Deutsche Bank said in an emailed statement: "We have been working diligently to further strengthen our systems and controls and are committed to being best in class. We have invested 3.6 billion euros(2.71 billion pounds) since 2012 as part of this effort."

The FCA declined to comment.

Germany's financial market watchdog Bafin also said on Friday it was examining whether Deutsche Bank properly followed disclosure rules with its fourth-quarter results published on Thursday.

(Reporting by Steve Slater and Huw Jones; Editing by Sinead Cruise and Mark Potter)