Hong Kong (CNN) -- The mayor of a Japanese city has sparked outrage after playing down a well-documented massacre of civilians in China's former capital more than 70 years ago.
An estimated 300,000 people died when Japanese troops invaded the city of Nanjing in China's Jiangsu province in 1937, unleashing a campaign of rape, murder and looting that became known as the Nanjing Massacre. The event was recently portrayed in a movie starring Christian Bale called "The Flowers of War."
But earlier this week, Takashi Kawamura, the mayor of Nagoya, told a visiting delegation from Nanjing that he believed only "conventional acts of combat" took place there, not the mass murders and rapes, China's state-run Xinhua news agency reported. He repeated his assertion to Japanese reporters Wednesday.
"It is true that a considerable number of people died in the course of battle. However such a thing as so-called Nanjing Massacre is unlikely to have taken place," he said.
"I have said that without hesitation since people from Chinese Communist Party came to visit us. If they think it is not fact ... they can tell us openly as they want. I am ready to hold an open debate in Nanjing to discuss it."
Kawamura's comments drew fierce criticism on mainstream and social media in China, while Nanjing officials announced they would be suspending ties with Nagoya. The two cities have enjoyed close links since establishing a sister-city relationship in 1978.
"The historical facts of the Nanjing Massacre have been solidly proven. The claim by Kawamura is extremely irresponsible. We hope the mayor can admit the historical facts and draw lessons from the past," read a statement issued by Nanjing's information office and published by Xinhua.
A spokesman for China's Foreign Ministry expressed support for the decision at a news conference Wednesday.
"We have made our position clear on the Nagoya mayor's denial of the Nanjing Massacre and already lodged a solemn representation to the Japanese side," Hong Lei said, in quotes carried by Xinhua. He added that China was closely monitoring the situation.
An editorial in the state-controlled Global Times Thursday urged China to put pressure diplomatically and economically on Kawamura to apologize or resign. "We strongly suggest China uses its diplomatic resources to issue sanctions on Kawamura and put pressure on Nagoya," it said.
"If needed, we can also downgrade economic cooperation with Nagoya to add weight to the incident. Such actions are totally morally justifiable. Most of the reckless Japanese officials to deny history like Kawamura had paid their price."
Sina Weibo, China's Twitter-like micro-blogging service, made the incident "topic of the day," attracting more than one million related posts at the time of writing, with many choosing to interpret Kawamura's comments as Japan's official attitude on the Nanjing massacre and other historical issues between the two countries.
One comment from a user known as Sunnyzhouchufei read: "I was planning a trip to Japan in March, now after the incident I'm calling it off. Many Japanese are a polite and well-educated people, but denial of [the] massacre reveals that they are really hypocrites. So this is my way of protest: I'll travel around the world, but never set my foot in Japan!"
Another, called Linglan, said: "Apparently Japanese government is conniving with such comments, otherwise how on earth can a Mayor be so reckless? He must have spoken what's on this militarist government's mind. This incident is in line with the government's long-standing attitude of denying the crime they once committed on other Asian countries. This is shameless, pathetic and hateful. China should halt all ties with Japan all together."
Meanwhile, city officials in Nagoya attempted to repair the damage. "What our mayor said is only his personal opinion. As a city government, we are to follow the national government's perception that the occurrence of [the] Nanjing Massacre can not be denied," said Kazuaki Enomoto, a spokesperson for Nagoya City Government.
"We have been working on building a relationship with Nanjing City for 34 years till now. We are not doing anything about the mayor's idea of a 'debate.'"
Kyung Lah in Tokyo and Shao Tian in Beijing contributed to this report.