Business billionaire and former New York mayor Michael Bloomberg has warned Brexit would damage Britain’s economy.

In another high-level foreign intervention in the campaign, Mr Bloomberg, who has an honorary knighthood, insisted he was not lecturing the British but expressing concern at the damage that would be done by exiting the EU.

“It’s not for me to tell British people how to vote, it’s for me to explain what – as an employer of 4,000 people in the UK, somebody who has a residence here, somebody who is building two of the most expensive buildings ever built here in the UK, in London, to make this our European headquarters – what it means for our employees, and what it means for our company, and what it means for America,” Mr Bloomberg told BBC Radio Four’s Today programme.

The ex-mayor, who has ruled himself out from running as an independent Republican candidate in the November US presidential election, said Britain has a strong position in the EU.

“I just think that the UK would be disadvantaged compared to the situation they are now. They have a special relationship with the rest of the EU. They have the borders that they can control, unlike the rest of the EU. They have a trade surplus with the rest of the EU. They have some abilities to influence the dialogue that without which they would, and America – which is my concern – would not benefit,” Mr Bloomberg said.

The business tycoon warned it would not be in the EU’s interest to do Britain any trade favours after Brexit.

“If they were to drop out it is really hard to see how they would ever negotiate a trade deal with the EU that gives them the benefits they have now. After all, the EU would have every interest to not give them those – that nobody else would drop out of the EU,” Mr Bloomberg said.

Rejecting talk of a loss of sovereignty, Mr Bloomberg said: “We all live in an international world, we all have agreements. American laws are made in the United States, EU laws are made in the EU, British laws are made in the United Kingdom. A very big part of the UK economy is based on exports to the EU, and other countries, so they certainly have an interest in the health of those other countries.”

Mr Bloomberg is one of the signatories to a letter to The Times stating that business investment decisions could be impacted by Brexit.

 

Mr Bloomberg was one of the signatories to a letter to the Financial Times from major overseas investors into the UK, who warned that the prospect of Brexit was “particularly concerning and potentially hugely damaging”.

“According to surveys, almost three-quarters of foreign investors cite access to the EU’s single market as a key reason for their investment in Britain,” said the letter.

“If there is one thing we as investors don’t like, it is economic uncertainty. As several important bodies have said – the International Monetary Fund, Bank of England, London School of Economics, the Treasury and others – leaving the EU would mean a shock to the UK economy, hurting growth, job creation and foreign investment. And no existing alternative outside can match EU membership in terms of access to the single market and a say over the rules governing trade and investment in that market.

“We are concerned this uncertainty, which would hang over the UK’s future trading relationship with the remaining EU states should it leave the single market, could materially affect major international businesses’ future investment decisions. As investors, it is therefore very much in our interests that Britain stays in the EU.”

Signatories to the letter included senior executives and chairmen from companies including Airbus, Mars, Cisco, Hitachi, Ford, Caterpillar, IBM and Microsoft.

Some of the signatories were hosted by David Cameron for a round-table discussion at 10 Downing Street.

Asked whether Mr Cameron had orchestrated the letter, a Number 10 spokesman said: “They are joining a litany of other businesses who have put their names to the debate to say the impact of leaving the EU would be negative for the UK economy and for their businesses.”