President Xi Jinping and other Chinese leaders have presided at a remembrance ceremony on the 77th anniversary of the Nanjing massacre amid a drive to revive memories of Japan's brutal invasion.
The Chinese president on Saturday said China and Japan should set aside hatred and not allow the minority who led Japan to war to affect relations now.
"The reason we are having a memorial for the Nanjing Massacre victims is to recall that all good-hearted people yearn for and hold fast to peace, not to prolong hatred," Xi said, in comments carried live on state television.
"The people of China and Japan should pass on friendship from generation to generation," he added.
"Forgetting history is a betrayal, and denying a crime is to repeat a crime. We should not hate a people just because a small minority of militarists set off an invasion and war ... but nobody at any time should forget the severe crimes of the invaders."
The Japanese slaughtered tens of thousands of Chinese civilians and soldiers when they occupied the city in December 1937.
Xi led officials gathered on Saturday morning at a memorial hall and museum in the former national capital.
After the national anthem, participants and people throughout the city stood for one minute of silence against the wail of what was described as the world's largest air raid siren.
Estimates of those killed in the massacre range from 40,000 to the official Chinese figure of 300,000.
About 20,000 women were also believed to have been raped over the six weeks of chaos, mass looting and arson.
A postwar Allied tribunal put the death toll at 142,000, but some conservative Japanese politicians and scholars deny a massacre took place.
China and Japan have fought over their history. In March, Japan lodged a protest with China over comments in Germany by Xi about the massacre.
Relations had deteriorated sharply over the past year following Shinzo Abe's visit to the Yasukuni Shrine honouring war criminals among Japan's war dead.
Tang Jiaxuan, a former Chinese foreign minister who heads a committee on improving relations with Japan, commented on the memorial last week.
"The 70th anniversary is an important opportunity for Japan to renew how it looks on and thinks of history, to unload its burden by facing up to and reflecting on history, to have real reconciliation with its Asian neighbours," Tang said.
The neighbours are also locked in dispute over islets in the East China Sea.
But both countries, mindful of the economic stakes, reached agreement last month to try to reset ties.
"China and Japan have a trading relationship worth many billions of dollars," Al Jazeera's Adrian Brown, reporting from Nanjing, said.
"Yet at times they still appear to be enemies. And it’s what happened here 77 years ago that still defines that problematic relationship."
Source: Al Jazeera and agencies