LONDON (AP) — A key executive from Deutsche Bank has said nearly half of its 9,000 U.K.-based jobs could be shifted out of Britain because of Brexit as industry leaders express concern about the lack of clarity in the process.

Chief regulatory officer Sylvie Matherat suggested that 4,000 back- and front-office positions could be forced to relocate once the country leaves the single market of 28 nations. Leaving could mean the loss of so-called "passporting" rights, a principle that allows any firm registered in one EU country to operate in any other member state without facing another layer of regulation.

Speaking Wednesday at the Frankfurt Finance Summit, Matherat says thousands of jobs could be lost to accommodate the change.

Matherat says "we really need clarity."