HSBC's plans to segregate its UK retail banking operations have hit a fresh obstacle after regulators indicated that a prospective candidate for the division's chairmanship would be inegible for the role, according to Sky News.Sky said that HSBC had held preliminary talks with the Prudential Regulation Authority (PRA), during which it indicated that it may want Alan Keir - the chief executive of HSBC Bank plc - to chair the new ring-fenced bank.The bank informally asked whether it was possible for a waiver of proposed rules that say a director is not dependent if he or she has been an employee of the ring-fenced body or of any other member of its group within a period of five years before his or her appointment as director, said Sky.The indication from the regulatory wing of the Bank of England is understood to have prompted HSBC to begin an external search for board members for its ring-fenced bank, even as speculation grows that Europe's biggest lender will spin off its UK business, the broadcaster said.The chair of a ring-fenced bank must be independent during his or her tenure on the board of the ring-fenced bank under the proposals.