Financial firms that offer services to customers in Britain directly from overseas without a base in the country must have executives that spend an "appropriate" amount of time on UK soil, the Financial Conduct Authority (FCA) said on Thursday.

Britain's "overseas persons exclusion" allows financial firms based outside the country to offer wholesale market services to customers in the UK without authorisation, one of the most liberal regimes globally.

Sarah Pritchard, executive director for supervision at the FCA, said there had been an uptick in such activity, which can make it harder for the watchdog to hold the firms to account when things go wrong, which could damage Britain's reputation in financial services.

"So it's for this reason that we expect senior managers to spend an appropriate amount of time in the UK, appropriate to their responsibilities," Prichard told a conference held by TheCityUK industry body.

"But at the same time we're working to ensure that the door is open to those who are operating in our markets and able to meet the standards that we accept," Pritchard said.

With pressure from industry and government to boost Britain's attraction at a global financial centre, it would be difficult for regulators to crack down too hard on foreign firms that make use of the overseas persons exclusion.

(Reporting by Huw Jones Editing by Mark Potter)