Vittorio Grilli, chairman of corporate and investment bank for EMEA at JPMorgan, said he could not see how the UK’s and EU would square their priorities in negotiations.
The bank chief added there is a lot of uncertainty surrounding Brexit and any talks with the bloc would have to wait till after the German elections.
Speaking to Bloomberg, Mr Grilli said: “[Divorces] are never pretty, but of course it depends on the two partners, ex-partners.
“Again, there was a lot of uncertainty toward the referendum, and that came out the way it did, and now elections in Great Britain on Thursday and there is still uncertainty there on exactly what the outcome is going to be.
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Vittorio Grilli said it was difficult to see a peaceful outcome after Brexit talks
“We have to see the outcome of that election. In ernest we have to wait for the German election as well.
“I think the subject matter is very very delicate and I think that it is very hard to see a very peaceful kind of outcome.
“I think there are major principles at stake. On one end, we know Great Britain – the issue of migration and control over their own borders is very important, then at the same time it is very important the issue of freedom of movement.
“So how do you square that? Right now, that in an agreeable manner is not obvious at all.”
I think that it is very hard to see a very peaceful kind of outcome
Mr Grilli said if Brexit negotiations go badly and companies fled the UK it would also have a negative effect on Europe as it took “centuries” to create the complex City hub.
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He said: “London was not created in one day, it took decades, if not centuries to create such an environment.
“It is a very complex environment and to recreate it somewhere else is not going to be easy. If London loses its own spesific way in the globe, Europe will also lose.”
It comes as Boris Johnson lashed out against the European Union for demanding an astronomical Brexit divorce bill, as he argued the UK could also reclaim money from the bloc.
The foreign secretary said: “We need to work inter-governmentally on all the issues. Indeed intensify our cooperation inter-governmentally with our friends and partners so as to create a deep and special partnership.
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“A new relationship based on trust and friendship between a strong UK and a strong EU. That is what we want to achieve, based on free trade and it’s something that can be immensely beneficial to this country.
“We can do, not just a great free-trade deal with the EU, but it will also enable us to go forward with free trade deals with the rest of the world and that is a genuinely exciting thing. We haven’t been able to do it for 45 years.
“I certainly don’t think there’s any case whatever for paying huge sums of money to the EU as some sort of Brexit settlement.
“There are huge sums of money we can take back and that we should take back control of, that can be used to the benefit of the people of this country.
“There’s a £10 billion net contribution we make every year, that must come back.”