Mayor of Japanese city of Nagoya Takashi Kawamura said at a debate of the city's mayoral election on Monday that he will not withdraw his denial on Nanjing Massacre that more than 300,000 Chinese were killed by Japanese Imperial Army in 1937, according to Japan's local media.

Kawamura told a Chinese delegation came from Nanjing in February 2012 that the Nanjing Massacre was probably not exist and the killed were normally died in war.

The mayor's irresponsible words triggered strong protest from all circles of Nanjing and the local government has suspended all official contact with Nagoya city.

Japanese troops killed more than 300,000 Chinese people, including a great number of civilians, including women and children, after they captured Nanjing on Dec. 13, 1937.

Japan's attitude towards history has been questioned by the countries that were invaded by Japan in the World War II, especially China and South Korea, and the two countries have urged many times that Japan should take a responsible attitude on history.

The historical issue has become an obstacle for Japan to improve its ties with its neighboring countries.