Britain's City of London financial district would have to give up its role in processing euro currency transactions after it leaves the European Union, French President Francois Hollande has warned.
Mr Hollande said other European financial centres should be ready to take on the role from London, which is home to many "clearing houses" that deal with euros.
"There is no reason for Europe, and still less the euro zone, to allow a country that is no longer a member of the European Union and has never been a member of the euro zone to continue operations in euros," Mr Hollande said after a summit of EU leaders in Brussels.
"What I want is that European financial centres prepare to take on a certain number of operations that can no longer be done in Britain," he added.
Britain's shock vote last week to leave the EU has sparked fears for its role as Europe's financial capital - and the world's biggest currency exchange hub.
The issue of whether euro clearing houses can remain in London is set to be one of the most contentious issues as Britain seeks to negotiate its future trade relationship with the EU after its departure.
Britain has jealously guarded its status and won a recent EU court decision against the European Central Bank in order to keep hosting the euro deals.
Jonathan Hill, a Briton, was the European Commissioner in charge of the coveted financial services portfolio until his resignation on Saturday following the referendum result.
