The two Asian powers traded blame over the aggression even as Chinese authorities allowed new protests in at least six cities.

''The Chinese government has never done anything that wronged the Japanese people,'' Chinese Foreign Minister Li Zhaoxing told his Japanese counterpart, who flew to Beijing to protest the violence.

Instead, Li said, Japan was to blame for ''a series of things that have hurt the feelings of the Chinese people'' over issues such as relations with rival Taiwan and ''the subject of history'' - a reference to new Japanese history textbooks that critics say minimize Tokyo's World War II-era atrocities.

Many Chinese believe Japan has never truly shown remorse for offenses committed during its invasion of China, including germ warfare experiments and sex slavery of thousands of women.

Japanese Foreign Minister Nobutaka Machimura arrived with relations between the two nations at their lowest point in decades.

Ill will has been brewing over gas resources in disputed seas and Tokyo's campaign to join China, Britain, France, Russia and the United States as a permanent member of an expanded U.N. Security Council.

Machimura called China's failure to apologize ''very unfortunate,'' Japan's Kyodo News agency reported.

''China's top leaders seem not to understand the huge shock that the Japanese public has felt over this issue,'' Machimura was quoted as saying.

Tensions reached a boiling point after the Japanese government approved a junior high school textbook earlier this month that critics said tried to whitewash Japan's wartime atrocities and justify its aggression in Asia in the first half of the 20th century.

On Saturday, police in Shanghai stood by as 20,000 protesters broke windows at the Japanese consulate, vandalized restaurants and damaged cars. Last week, protesters smashed windows at the Japanese Embassy in Beijing.

''We believe that the lack of adequate security measures was one of the main causes of this kind of damage,'' Japanese Foreign Ministry spokesman Hatsuhisa Takashima said. ''This kind of situation does not help in any way to improve relations between [the] two countries.''

The consulate in Shanghai also was ringed by hundreds of police, some armed with shields, but there was no sign of new protests. The consulate's walls were splattered blue and black from paint bombs. A notice on the consulate Web site told Chinese visa applicants to stay away.