A number of London-based banks could be forced to relocate their workforce to Paris and Frankfurt if Britain chooses to leave the European Union, the EU's financial services commissioner said on Wednesday (22 June).

Speaking to German business newspaper Handelsblatt, Jonathan Hill warned that a Brexit would have a severe impact on the UK's financial and banking sector.

"I've visited London, Manchester and other British financial centres in the past weeks and warned of the consequences of an exit from the EU," he said.

"Then it could happen that banks and investment funds shift activities and jobs to Frankfurt and Paris."

Earlier this month, US investment bank JP Morgan described a Brexit as a "terrible deal" for the British economy and warned it could cut up to 4,000 jobs itself if the UK votes in favour of leaving the EU.

Hill's and JP Morgan's fears echoed a warning issued by rating agency Standard & Poor's, which suggested Britain's role as Europe's financial centre could be in danger in the event of a Brexit.

Back in March, the rating agency warned international banks could refocus their European businesses away from Britain, particularly if the UK was no longer part of the passporting arrangement – which allows credit institutions from EU countries to carry out their business in another member state without having to obtain an official authorisation from the relevant regulator.

"A vote to leave would result in complex, prolonged negotiations with the EU over the terms of the UK's exit, with considerable uncertainty over the outcome," S&P said in a statement.