Weidmann, a member of the European Central Bank's governing council, was hired in 2011 and his first term expires in April. Asked whether Weidmann would stay on, the source said: "That's how it will play out."

The extension would in theory keep Weidmann in the mix as a possible successor to ECB chief Mario Draghi, whose job will become available at the end of October, although Bank of France Governor Francois Villeroy de Galhau is seen as the frontrunner.

No serious discussion is likely on the Draghi succession until after the European Parliament elections this spring, when the ECB job is expected to be decided in a package that also includes the heads of the European Commission and Council.

(Reporting by Holger Hansen and Douglas Busvine; Editing by Joseph Nasr and Gareth Jones)