BEIJING China's Foreign Ministry has criticized remarks by a board member of Japan's state broadcaster who said a massacre carried out by Japanese troops in China's then-capital of Nanjing in 1937 did not happen.
China consistently reminds people of Japan's historical brutality, such as the Nanjing Massacre in which China says Japanese troops killed 300,000 people.
A post-war Allied tribunal put the death toll at 142,000, but some conservative Japanese politicians and scholars deny a massacre took place.
Naoki Hyakuta, a member of NHK's board of governors who is also a novelist and commentator, was quoted by Japanese media this week as saying the Nanjing Massacre did not happen.
In a later follow-up on Twitter, he said it was unclear how many people had been killed in Nanjing.
China's Foreign Ministry said in a statement released late on Wednesday such remarks were "a barefaced challenge to international justice and human conscience".
"The Nanjing massacre was a brutal crime committed by the Japanese militarists during their invasion of China, which has irrefutable proof. The international community has long ago reached a verdict about it," the ministry said.
"A handful of people in Japan have tried to blot out, cover up and distort that history," it said. "Such behavior is in the same line as those of some Japanese leaders who try to reverse history. The international community should be highly vigilant at this."
China's ties with Japan have long been poisoned by what Beijing sees as Tokyo's failure to atone for its occupation of parts of China before and during World War Two.
Deteriorating relations between Beijing and Tokyo have been fuelled by a row over a chain of disputed islands in the East China Sea. Ships from both countries frequently shadow each other around the islets, raising fears of a clash.
Ties have further worsened since China's creation of an air defense identification zone over the East China Sea and Japanese Prime Minister Shinzo Abe's visit to the controversial Yasukuni Shrine honoring war criminals among Japan's war dead.
(Reporting by Ben Blanchard; Additional reporting by Elaine Lies in TOKYO; Editing by Paul Tait)