The chief executive of Goldman Sachs has issued another scathing warning on the effects of Brexit, saying that the City of London will “stall” because of the risks associated with the process of the split.

Speaking to the BBC, Lloyd Blankfein said that both sides of negotiations were playing for very high economic stakes and that there would have to be a period of implementation of at least “a couple of years” after a deal has been concluded, slated for the spring of 2019.

He said that if there was no such period, banks like Goldman Sachs would have to act “prematurely”.

“We are talking about the long-term stability of huge economies with hundreds of millions of people and livelihoods at stake and huge gross domestic product,” he told the broadcaster.

“So, if it takes a little while – I'd rather get it right than do things quickly.”

Goldman employs about 6,500 people in the UK, and Mr Blankfein said that the lender has “contingency plans” to relocate people depending on the outcome of negotiations, though he hopes that this would not end up being necessary.

Asked whether London’s rapid expansion as a global financial hub in recent years could reverse as a result of Brexit, Mr Blankfein said that it “would stall” and “might backtrack a bit” but that it was unlikely to “totally reverse”.

“It just depends on a lot of things about which we are uncertain and I know there isn’t certainty at the moment,” he said.

Mr Blankfein’s comments echo those made by the bank’s Europe chief executive, Richard Gnodde, in March.

In an interview with CNBC, Mr Gnodde said that Goldman had started planning relocations even before Theresa May triggered Article 50 on 29 March.

The financial sector is crucial to the UK economy and contributed about £71bn to the Exchequer last year, according to professional services firm PwC.

Most banks have made clear that they will be forced to move some staff and are making contingency plans for a number of potential Brexit outcomes.

Earlier this week, JP Morgan confirmed that it would move hundreds of jobs from the UK to the EU because of Brexit.

In pictures: European parliament Brexit discussions Show all 12 1 /12 In pictures: European parliament Brexit discussions In pictures: European parliament Brexit discussions European commission member in charge of Brexit negotiations with Britain, French Michel Barnier listens at the President of the European Commission Jean-Claude Juncker speaking at the European Parliament in Strasbourg Getty Images In pictures: European parliament Brexit discussions Frank-Walter Steinmeier, President of the Federal Republic of Germany, delivers his speech at the European Parliament in Strasbourg EPA In pictures: European parliament Brexit discussions European Union's chief Brexit negotiator Guy Verhofstadt, President of the Group of the Alliance of Liberals and Democrats for Europe (ALDE), addresses the European Parliament during a debate on Brexit priorities and the upcomming talks on the UK's withdrawal from the EU Reuters In pictures: European parliament Brexit discussions Michel Barnier, European Chief Negotiator for Brexit reacts during a meeting at the European Parliament in Strasbourg EPA In pictures: European parliament Brexit discussions Member of the European Parliament and former leader of the anti-EU UK Independence Party (UKIP) Nigel Farage wears socks with Union Jack flag at the European Parliament in Strasbourg Getty Images In pictures: European parliament Brexit discussions Nigel Farage, United Kingdom Independence Party (UKIP) member and MEP, addresses the European Parliament during a debate on Brexit priorities and the upcoming talks on the UK's withdrawal from the EU Reuters In pictures: European parliament Brexit discussions European commission member in charge of Brexit negotiations with Britain, French Michel Barnier gestures during speeches at the European Parliament in Strasbourg Getty In pictures: European parliament Brexit discussions The President of the European Commission Jean-Claude Juncker (L) speaks with European commission member in charge of Brexit negotiations with Britain, French Michel Barnier at the European Parliament in Strasbourg Getty In pictures: European parliament Brexit discussions European Union's chief Brexit negotiator Guy Verhofstadt, President of the Group of the Alliance of Liberals and Democrats for Europe (ALDE), addresses the European Parliament during a debate on Brexit priorities and the upcomming talks on the UK's withdrawal from the EU Reuters In pictures: European parliament Brexit discussions Member of the European Parliament and former leader of the anti-EU UK Independence Party (UKIP) Nigel Farage gestures during speeches at the European Parliament in Strasbourg, eastern France, on April 5, 2017. The European Parliament will on April 5 lay down its "red lines" for negotiations over a Brexit deal, on which the assembly will have the final say in two years' time. / AFP PHOTO / Sebastien BozonSEBASTIEN BOZON/AFP/Getty Images Getty In pictures: European parliament Brexit discussions German president Frank-Walter Steinmeier delivers a speech during a plenary session at the European Parliament in Strasbourg Getty In pictures: European parliament Brexit discussions The European Parliament in Strasbourg, eastern France Getty Images

In January, Stuart Gulliver, chief executive of HSBC, said trading operations that generate about 20 per cent of revenue for the lender’s investment bank in London may move to Paris.

Axel Weber, chairman of UBS, said in January that about 1,000 of the bank’s 5,000 jobs in London could be at risk.