A top Treasury official has said that the total number of Brexit-related banking job moves is "currently unknown", raising questions about the scale of losses to London's financial services industry after Britain leaves the EU.
Katharine Braddick said the impact on jobs has so far been minimal across the financial services industry, and played down suggestions that all banks had already made decisions to shift staff away from London to Germany's financial hub.
Speaking at the Frankfurt Finance Summit, she said: "What we see in the UK is an initial set of moves which are to do with essentially hedging the immediate risks to ensure that clients and boards can be assured that services continue in a way that is not only undisrupted, but completely sound from a regulatory and legal standpoint.
"And that first phase of moves is, I think, relatively confined."
However, the Treasury's director general of financial services said most firms expect there to be a second wave of job moves - but said the total figures were unknown.
"Depending on the relationship that we achieve with the European Union - and of course our aspiration is a very close relationship on financial services - that will determine the scale of that second phase and to me that's currently unknown," Ms Braddick said.
It raises questions about the composition of the financial services industry post-Brexit.
Frankfurt Main Finance, which organised the conference, has forecast that the City of London could lose as many as 20,000 to 25,000 jobs as a result of Brexit, with 10,000 ending up in Frankfurt.
Without a deal, businesses are expected to shift EU-focused operations and key staff to rival financial hubs including Dublin, Paris, Frankfurt and Luxembourg.
JP Morgan is ramping up a number of EU sites, with plans to move up to 1,000 London front and back-office roles, while EU lender Deutsche Bank is preparing to settle more of its transactions out of Frankfurt and is likely to move hundreds of staff from London.
Separately, HSBC has said it is on course to move up to 1,000 jobs to France.
Goldman Sachs - which employs 6,500 UK staff - is set to at least double its Frankfurt workforce to 400 through a mixture of relocations and local recruitment and has also signed a lease on a yet-to-be-built skyscraper that can house up to 800 employees, with options to take up additional space.
A raft of Asian banks including Nomura, Daiwa, Sumitomo Mitsui Financial Group (SMFG) and Mizuho Securities are also on track to expand their operations in the German financial hub.
Ms Braddick's comments come after reports emerged suggesting tensions have been growing between the Treasury and Bank of England over post-Brexit regulation of the City.
Tension between the Treasury and Bank of England has been sparked by the EU's rejection of a "mutual recognition plan" which would have given the Bank the regulatory control it seeks, the Financial Times has said.
The Treasury is seeking to keep controls as closely aligned to Brussels as possible to assure maximum City access to the EU market, while the BoE is against any compromise that would leave it a "rule taker" of the bloc's regulations, according to the newspaper.