Wuermeling's comments come just days after Deutsche Bank and Commerzbank, Germany's top two lenders, announced they were in merger talks.

Wuermeling, without naming Deutsche or Commerzbank, added that supervisors will be neutral in evaluating any merger proposals and they will never actively initiate them.

"Mergers require a viable and sustainable business model," Wuermeling told a conference. "The assumptions and projections in the submitted business plans will therefore be thoroughly analysed."

(Reporting by Balazs Koranyi; Editing by Catherine Evans)