BEIJING: China said on Wednesday that Japan had acted irresponsibly by withholding its 2016 funding for the UN heritage body UNESCO in a row over how the 1937 Nanjing Massacre is remembered.

UNESCO last year decided to include documents about the massacre in its "Memory of the World" programme.

Chinese Foreign Ministry spokeswoman Hua Chunying said the massacre was a serious crime and a historical fact recognised by the international community, and UNESCO was right to include it in the listing.

"What Japan has said and done once again lays bare their wrong attitude of not acknowledging history," Hua told a daily news briefing in Beijing. "Not paying fees to UNESCO to exert pressure is irresponsible. They will not achieve their aims."

Ties between China and Japan, the world's second- and third-largest economies, have been plagued with a territorial dispute over a group of tiny East China Sea islets and the legacy of Japan's wartime aggression.

China says Japanese troops killed 300,000 people in 1937 in its then capital of Nanjing. A postwar Allied tribunal put the death toll at 142,000, but some conservative Japanese politicians and scholars deny a massacre took place at all.

UNESCO established the "Memory of the World" programme in 1992 to protect important historical documents and materials.

Japan last year raised questions about the authenticity of the Nanjing Massacre documents submitted by Chinese organisations for the inclusion in the programme and asked for fairness and transparency, prompting an angry retort from China.