A number of banks have put off possible investments in Britain until after a referendum on its future in the European Union, a lobby group said on Tuesday, after Deutsche Bank revealed it was considering cutting down its UK operations should the country pull out.

With banks complaining about uncertainty on the EU question and “punitive” tax increases, the British Bankers’ Association also said a former financial regulator would lead a review of Britain’s competitiveness on behalf of the industry and report to the government.

Prime minister David Cameron has promised to renegotiate Britain's relationship with the EU and then hold the referendum by the end of 2017 on whether to stay in the region or leave.

Deutsche Bank, the euro zone’s second-largest bank by assets and which has almost 9,000 staff in Britain, has formed a working group to consider moving some operations to Germany or elsewhere in the euro zone in case of a “Brexit”, a spokeswoman for the bank said.

It is not the only one to rethink its operations, according to the BBA, which lobbies on behalf of UK and international banks.

“Some banks have recently moved operations and jobs out of the UK due to punitive hikes in bank taxes. Other banks have deferred decisions about whether to invest in Britain until after the referendum,” said BBA chief executive Anthony Browne.

The BBA said Hector Sants, who led the now defunct Financial Services Authority, and consultancy Oliver Wyman should deliver their competitiveness report to the government with a series of recommendations in the autumn.

Goldman Sachs, JPMorgan, Bank of America Merrill Lynch and Morgan Stanley said they had not made any formal contingency plans for an EU departure. However, banks with large operations in Britain are expected to begin examining the implications and whether this might limit Britain's access to its largest trading partners in Europe.

Deutsche Bank’s working group - which includes executives in strategy, risk, UK management and research divisions - will examine different Brexit scenarios and their implications for the bank’s large business in Britain, the spokeswoman said.

Deutsche has 16 locations in Britain, down from 21 five years ago. Its presence in Britain since dates back to 1873.

Bank of England Governor Mark Carney said last week it was important that the British government provide clarity on how it will proceed with the referendum, which could be held as soon as next year.

A Downing Street spokesman had no immediate comment.

HSBC is also reviewing whether it should move its headquarters from London and has said it would make its decision in a few months. If it moves it would most likely be to Hong Kong, where it was based before moving to London in 1993.

Speaking to Reuters last week, HSBC chairman Douglas Flint said the uncertainty of the vote could impact investment plans across the banking sector.

“Our economic analysis says that the balance of advantage lies with staying in Europe and working within Europe to make it more competitive. More stability and certainty is better for economic progress, because people can make decisions if they can foresee what the framework of policy is going to be,” Flint said. Reuters