China has told Japan that "negative" moves by Tokyo on major issues are preventing an improvement in bilateral ties, but there are now opportunities to improve China-Japan relations.

Chinese Foreign Minister Wang Yi told his Japanese counterpart Fumio Kishida during a meeting in Germany that both countries should make efforts to bring bilateral ties back onto the right track.

"There are now both opportunities and challenges for improving China-Japan relations," China's Foreign Ministry paraphrased Wang as saying in a statement late on Friday.

"The continuous, negative moves made recently by Japan regarding major sensitive issues have caused disturbances to the improvement of bilateral ties," Wang added, without offering details.

"Only when Japan honours its commitments and adopts a responsible attitude, thus preventing the occurrence of incidents damaging the political foundation of the China-Japan ties, can there be real improvement in relations."

The two were meeting on the sidelines of a gathering of foreign ministers of the G20 top economies in the German city of Bonn.

Ties between Asia's two largest economies have long been overshadowed by arguments over their painful wartime history and a territorial spat in the East China Sea over a group of uninhabited islands, among other issues.

China this week expressed concern after Japan got continued U.S. backing for its dispute with Beijing the islands during a meeting between U.S. President Donald Trump and Japanese Prime Minister Shinzo Abe.