Boerner said he also feared the continuation of Japan's monetary policy could send the euro rising higher against the dollar to above the 1.40 level. But he did not expect the Japanese easing and accompanying rise in the euro's exchange rate would seriously undermine German exports.

The BOJ has already slashed interest rates close to zero and said on Tuesday it would switch to an open-ended commitment of buying assets next year and double its inflation target to 2 percent.

(Reporting by Gernot Heller; writing by Erik Kirschbaum)