FRANKFURT, Jan 2 (Reuters) - The National Bank of Belgium is debating options to retain its governor after the mandate of Pierre Wunsch, an influential voice on the European Central Bank's Governing Council, expired on Monday, a bank spokesman said on Tuesday.

The prime minister has asked the bank to extend the term of Wunsch, using the principle of continuity of public service, a stopgap measure the could keep him in office until a formal decision on his reappointment could be made, the spokesman said.

Political wrangling among Belgium's top parties has stopped the appointment of several high ranking public officials in recent months, even as the government said it would like to retain Wunsch for another four year term.

(Reporting by Balazs Koranyi; Editing by Alison Williams)