Germany's biggest lender has set up a working group to formally examine the impact of a British referendum on EU membership, set to be held by 2017, the spokesman said in an emailed response to AFP.

The working group included senior executives in charge of the bank's strategy, risk, UK management and research divisions.

And they would “do scenario-based planning on implications on our presence in the UK, including whether it would be advantageous for certain activities to be repatriated to the eurozone, specifically to Germany,” the spokesman said.

Deutsche Bank has been present in Britain since 1873 and employs just under 9,000 people at 16 different locations there, he said.

“Unlike other banks, our review is not based on the UK banking levy, but on the 'Brexit' potential,” the spokesman said, using the shorthand expression for a British EU exit.

Under Prime Minister David Cameron, Britain introduced a banking levy – imposed on lenders' balance sheets – in 2010, which has since been hiked eight times, most recently in April.

Other banks, such as Standard Chartered and HSBC, have said they are currently reviewing their British base, citing also tighter regulation and rising taxes.

Debate about a possible “Brexit” has intensified following the victory of Cameron's Conservative party in this month's general election, and their promise to let Britons vote by 2017 on whether to stay in or leave the European Union.

At the moment, however, most experts do not believe that Britain will actually quit the 28-nation bloc.

Cameron says he wants Britain to remain in the EU, but only if he can secure reforms such as changes on migration and benefits, and the repatriation of certain powers from Brussels to London.