Deutsche Bank's chief executive has warned UK staff that roles may be shifted to Frankfurt as it prepares for a Brexit outcome that is "worse than people can imagine".
John Cryan delivered the message in a video posted on the company's intranet on July 11, adding that the German bank was likely to book the "vast majority" of its assets out of Frankfurt - where its headquarters are based - after Brexit.
Mr Cryan told employees that the bank was preparing for a worst-case scenario from Brexit talks.
"There's an awful lot of detail to be ironed out and agreed; depending on what the rules and regulations turn out to be, we will try to minimise disruption for our clients and for our own people.
"But inevitably roles will need to be either moved or at least added in Frankfurt," Mr Cryan said in the video, details of which were first reported by Bloomberg.
The Yorkshire-born chief executive added: "We will assume a reasonable worst outcome. The worst is always likely to be worse than people can imagine."
Deutsche Bank declined to comment.
Mr Cryan's comments throw up questions about Deutsche Bank's commitment to London, particularly surrounding its arrangements for a new UK headquarters.
In March, the German banking giant entered into exclusive negotiations with Land Securities on a new building currently being constructed in the City at 21 Moorfields, with plans to take on a 25-year lease.
Deutsche has told staff they would start being transferred to the new site during the second half of 2023, though the move was subject to planning consent and a lease being agreed.
No further details on the status of those plans have been released.
Deutsche Bank is one of the first European financial services firms to signal a shift of jobs back to the Continent as a result of Brexit.
Most relocation announcements have come from non-EU banks and insurers, many of which will have to apply for full licences within the 27-nation bloc that will give them access to the single market for financial services once the UK scraps its own membership.
Banks including Standard Chartered, Japan's Daiwa and Sumitomo Mitsui Financial Group (SMFG), as well as South Korea's Woori Bank have all confirmed plans for subsidiaries in Frankfurt.
Others including JP Morgan have indicated plans for a pan-European strategy, with proposals to spread staff across sites including Dublin, Luxembourg and Frankfurt.
The Press Association understands that Morgan Stanley has also chosen Frankfurt as the site of its post-Brexit hub, while Citi is expected to confirm its own plans to bulk up its own German office later this week.