Chinese soldiers laid wreaths on Tuesday at a ceremony to mark the 1937 massacre of civilians in the Chinese city of Nanjing by Japanese troops.

The televised event at the Nanjing Massacre memorial recalls an incident in which China says Japanese soldiers killed 300,000 people in the city that was then its capital.

A postwar Allied tribunal put the toll at 142,000, but some conservative Japanese politicians and scholars deny a massacre took place at all.

The massacre could never be denied, however, said Zhao Leji, a member of China's Politburo, a top decision-making body of the ruling Communist Party, in a speech transmitted live by state broadcaster CCTV.

"All hideous activities that attempt to change history, deny the violent activities and reverse the verdict of starting the aggression war will be criticized and spurned by Chinese people and anyone who loves peace and justice in the world," he said.

People walk past a monument as China holds a memorial ceremony to mark the National Memorial Day for Nanjing Massacre Victims in Nanjing, Jiangsu province, China, December 13, 2016.

Television images showed government officials, war veterans and school children singing the Chinese national anthem. Doves were released and flew overhead as a giant bell tolled to end the ceremony.

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

In October, Japan withheld its 2016 funding for UNESCO, following the UN heritage body's decision last year to include documents about the Nanjing massacre in its "Memory of the World" program.

UNESCO set up the program in 1992 to protect important historical documents and materials.

Last year, Japan raised questions about the authenticity of the Nanjing Massacre documents submitted by Chinese bodies for inclusion in the program and urged fairness and transparency, prompting an angry retort from China.