The website of a city-run zoo in Nagoya was hacked to display messages demanding that Japan acknowledge the 1937 massacre of Chinese civilians in Nanjing, officials said.
The posted messages, which included kanji believed to show a Chinese personal name, followed Nagoya Mayor Takashi Kawamura's recent denial of the Nanjing Massacre.
The posting in Japanese included messages stating "The history is manipulated!" and "Please acknowledge the Nanjing Massacre!" displayed along with a full-body photo of a man, which appeared after clicking on Chinese characters shown on the top page of the website, city officials said.
On Monday, the 63-year-old mayor told a visiting Nanjing city official that he believes only "conventional acts of combat" took place in Nanjing, not mass murder and rape of civilians, drawing criticism from China.
An employee of the Higashiyama Zoo and Botanical Gardens became aware of the messages around 8:45 a.m. Thursday. The city reported the incident to police after deleting the messages.
The Nanjing Massacre by Imperial Japanese Army soldiers occurred in 1937. China says the number of victims totaled more than 300,000, but Japanese academics point to various estimates ranging from 20,000 to 200,000.