Dutch Prime Minister Mark Rutte has questioned British optimism that leaving the EU will lead to a brighter future, saying the UK could be in for "potentially irreparable harm".
In unusually frank terms toward a long-standing allied nation, Mr Rutte said Britain's economic growth has remained good since last year's Brexit vote only because the pound has sunk.
"If you look below the surface, the English economy suffers potentially irreparable harm because of their Brexit," he warned.
Mr Rutte said the Brexit vote has already led to a "tectonic shift" within the international banking community that still has London as one of its biggest global hubs.
He said American banks are seeking to get out of the City of London and have shown a keen interest in Amsterdam as a new hub.
"They want to leave London, so they mainly think about Frankfurt and Amsterdam," he said.
Prime Minister Theresa May is expected to officially launch divorce proceedings with the EU by the end of the month, setting off two years of negotiations to disentangle itself from its 27 partners.
Britain also needs to negotiate a new trade agreement with the bloc.
"I don't see right away how they can negotiate a deal with Europe in the future. It will never be as good as what they have now," Mr Rutte said, adding the trade relationship with the continent "is getting really in danger".
He noted that SNP politicians want to hold another vote on Scottish independence just as the UK is negotiating its exit from the EU.
And, he added, by leaving the EU, the UK - and Northern Ireland - could get a hard border with EU member Ireland on the politically sensitive island.
"The political system in London is shaking on its foundations. You don't want that," said Mr Rutte, comparing Brexit to suggestions from some of his political rivals that the Netherlands leave the EU, too.