China wants to make World War II a key part of a trip by President Xi Jinping to Germany next month, much to Berlin's discomfort, diplomatic sources said, as Beijing tries to use German atonement for its wartime past to embarrass Japan.

China has increasingly contrasted Germany and its public contrition for the Nazi regime to Japan, where repeated official apologies for wartime suffering are sometimes undercut by contradictory comments by conservative politicians.

Ties between the two Asian rivals worsened when Prime Minister Shinzo Abe visited Tokyo's Yasukuni Shrine on Dec. 26, which China sees as a symbol of Tokyo's past militarism because it honors wartime leaders along with millions of war dead.