According to the Financial Times, the watchdog said that "during this period of uncertainty" financial operations of UK expats in Europe may be compromised and suggested that clients of UK banks in Europe refrain from providing their banking details to suspicious agents.
The watchdog added that UK banking consumers inside the country should be unaffected, as branches of European lenders located in the United Kingdom are controlled by domestic regulators.
The warning comes amid uncertainties in the future of the UK-EU post-Brexit arrangements. The Brexit negotiations have turned out to be tougher than expected for both sides, with neither able to agree on major points such as the Irish border and post-Brexit trade tariffs with third parties.
Meanwhile, the prospect of UK leaving the bloc without a deal looms large as the negotiations are scheduled to conclude by the end of March 2019.