Chinese estimates put the figure of dead civilians, including women and children, at more than 300,000 Chinese, slaughtered within six weeks of the army entering the city -- then the Chinese capital, called Nanking.
An exact tally is difficult, although an inquiry by the International Military Tribunal for the Far East -- also known as the Tokyo War Crimes Tribunal -- put the figure of dead civilians and prisoners of war "over 200,000."
When it became apparent Japan would surrender, "an organized effort [by Japanese troops] was made to burn or otherwise destroy all documents and other evidence of ill-treatment of prisoners of war and civilian internees," the tribunal said in its 1948 report.
Japanese media this week quoted NHK commentator and board member Naoki Hyakuta, who also is a novelist, saying the Nanjing massacre didn't happen.
China's Foreign Ministry spokesman Hong Lei said that such behavior is "a barefaced challenge to international justice and human conscience," China's official state news agency Xinhua reported.
"The Nanjing massacre is a brutal crime committed by Japanese militarism during their invasion of China, which has irrefutable evidence. The international community already had a verdict about it," Hong said in a written ministry statement.
"A handful of people in Japan have tried to blot out, cover up and distort that history," the statement 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."
Hong urged Japan to face up to, and deeply reflect on, the truth about the invasion, Xinhua reported.
The row over Hyakuta's comment comes after NHK's new chairman Katsuto Momii recently said the Japanese army's use of "comfort women" was "common in any country at war," Japan's news agency Kyodo reported.
Momii, speaking at a news conference to mark the start of his three-year stint as chairman, said forcibly recruiting women to work in brothels specifically for soldiers was considered wrong only in light of "today's morality."
Momii later apologized for his comments. But his remarks, and those of Hyakuta, sparked widespread anger in China and other South Asian countries that were occupied by Japan before and during the second world war.
Sino-Japanese relations have been strained since China began claiming its territorial waters extend deep into the South China Sea to islands controlled by Japan, as well as islands controlled by other countries.
China also complained bitterly this week about comments by Philippines President Benigno S. Aquino III in an interview with the New York Times.
Aquino, seeking greater support from other nations for the Philippines' effort to resist China's maritime claims, recalled the West's appeasement of Adolf Hitler's Nazi Germany by not supporting Czechoslovakia.
Xinhua reported Aquino's comments were "inflammatory" and they "senselessly compared his northern neighbor [China] to the Nazi Germany, exposed his true color as an amateurish politician who was ignorant both of history and reality."