BERLIN (Reuters) – Britain and the remaining 27 members of the European Union should stay away from the cliff edge of Britain falling back on World Trade Organization terms at the end of Brexit negotiations, Eurogroup chairman Jeroen Dijsselbloem said.

“Let’s try to minimize the damage,” he said of Brexit, speaking at a banking conference in Berlin on Thursday.

Dijsselbloem, who said he would discuss Greece with German Finance Minister Wolfgang Schaeuble while in Berlin, said the more he thought about Brexit, the more worried he became. He singled out financial stability as one area of particular risk.

Asked about “passporting” rights for Britain-based institutions to sell financial services in the EU single market after Brexit, Dijsselbloem replied: “I think, also talking to financial players from the City, that passporting won’t be the answer. There will be different regimes for different sub-sectors of the financial sector.”

“Equivalence will be part of the solution,” he added of a system whereby Brussels grants access to non-EU firms that comply with rules similar to those in the bloc.

“But here again, declaring the rules and regulations and the supervision of the UK equivalent to that of the EU at the outset is quite easy, but over time our standards and the way of supervision will start to diverge,” Dijsselbloem said.

“So if you want to maintain equivalence over time you will have to commit, also in the long-run, to staying close to the European standards,” he added. “Looking to the future, we will have to find to ways to regularly assess whether we are still equivalent.”

(Writing by Paul Carrel Editing by Jeremy Gaunt)