"The Japanese side should learn a lesson from history, especially during World War II, to prevent history from repeating itself," Chinese Foreign Ministry spokeswoman Zhang Qiyue told a news conference.
Mori scrambled to defend his remarks after making the comments about the emperor and Japan on Monday night at a meeting of lawmakers and Shinto religious leaders in Tokyo.
He said the statements were made in the context of Japan's history and culture and had nothing to do with the nation's political system.
"The comments do not contradict the postwar principle that sovereignty rests with the people," he told reporters Tuesday.
Nevertheless, Mori's comments sparked a furious response from opposition leaders in Japan and are likely to set off a furor across Asia, where many nations remain sensitive to any statement hinting at a military revival in Japan.
"We hope the Japanese side can seriously and responsibly handle the historical problems concerned and not do anything to hurt the feelings of the Chinese and other Asian peoples," Zhang said.
China in particular suffered in the 1930s and 1940s when large parts of the country were occupied by Japanese troops.
"We hope the Japanese people acknowledge that Japan is a divine nation centering on the emperor," Mori said at Monday's 30th anniversary of the Shinto Political Federation Lawmakers Gathering. "Education reform led by regional (Shinto) guardian deities and shrines should be carried out."
Shinto, which is indigenous to Japan, teaches that the world is full of gods called kami, dominated by the sun goddess Amaterasu - from whom the Emperor is said to be descended.
The religion became a tool of nationalists early in the 20th century and was the official religion of the Japanese armies, which attacked and conquered much of Asia in the name of the emperor in the years 1937-1945.
After World War II, Shinto was stripped of most of its nationalistic connotations and the emperor officially ceased to be divine. Japan's constitution now prohibits any link between religion and the state.
Relations between Japan and China have been strained periodically by remarks by Japanese nationalists whitewashing Tokyo's atrocities in China during and before World War II.
"To properly handle and have a correct understanding of history is an important political basis for developing a friendly cooperative relationship between China and Japan," Zhang said.
Mori has publicly said that he was not sure Japan's military presence in China was invasive.
Mori's comments were believed to be an attempt to woo support from religious groups ahead of a general election virtually certain to be held on June 25
But they could well backfire by igniting opposition from civil liberties groups.
Mori has come under fire for political gaffes in the past, including statements about AIDS and crime in the United States.
Just last week he found himself in hot water over a tabloid magazine story, which said police caught him in a brothel during a 1958 raid on Tokyo red light districts. Mori demanded a retraction and an apology. The magazine refused.
And in March Mori angered many people in the southern state of Okinawa by saying that teachers there opposed the government's new policy requiring the national anthem at functions because they were "controlled by communists."
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