"Here in UK, lots of hand-wringing from CEOs over #Brexit," Blankfein wrote on Twitter while in London for a client event.

"Better sense of the tough and risky road ahead. Reluctant to say, but many wish for a confirming vote on a decision so monumental and irreversible. So much at stake, why not make sure consensus still there?"

It was not immediately clear what he meant by a confirming vote. A Goldman Sachs spokesman in London declined to comment or elaborate further.

A spokesman for the Department for Exiting the European Union said there would be no second referendum.

Ever since the vote, opponents of Britain’s exit - from French President Emmanuel Macron, to former British prime minister Tony Blair and billionaire investor George Soros - have suggested Britain could change its mind and avoid what they say will be disastrous consequences for the British economy.

"Clearly the Goldman CEO only believes in democracy when it goes along with the views of a few CEOs. His comments show how out of touch he is with the concerns of ordinary people," said Richard Tice, co-chair of the Leave Means Leave campaign group, which is pushing for a so-called hard Brexit.

Blankfein, a relative newcomer to Twitter, sparked a wave of speculation last month when he tweeted that he was planning to spend a lot more time in Frankfurt.

Goldman Sachs donated a six-figure sum to the campaign to keep Britain inside the European Union in 2016.

Britain is currently home to most of the Wall Street bank's European operations, where it has around 6,000 employees. But the firm needs to ensure it will still be able to serve clients in the EU once Britain leaves the bloc and may have limited access to the EU's single market.

Goldman has agreed to lease office space at a new building in Frankfurt, giving it space for up to 1,000 staff.

The Wall Street bank is also building a 1.1 million square-foot office in London with initial occupancy slated for 2019, and Blankfein has also tweeted that he still expects to fill these new European headquarters.

In a tour of European cities in the past few months, Blankfein also praised France while in Paris for its strong government and good food. [L8N1NK8BH]

(Reporting By Anjuli Davies and Andrew MacAskill, editing by Guy Faulconbridge and Jon Boyle)

By Anjuli Davies and Andrew MacAskill