Thousands of Chinese marched in the streets in sometimes violent protests Saturday against Japan and its claim to disputed islands, a show of anger far larger than past protests over the competing territorial claims.
Photos from the southwestern city of Chengdu and the central city of Zhengzhou showed hundreds of people marching with banners and signs protesting Japan's claim on what China calls the Diaoyu islands. Japan calls them the Senkaku islands.
Japanese retailers Ito-Yokado and Isetan said protesters in Chengdu broke windows and showcases in their stores, Kyodo News agency reported.
China's state-run Xinhua News Agency said more than 2,000 people protested in Chengdu and thousands of college students gathered in the northern city of Xian.
The report was in English only. The protests were not reported in Chinese-language state media, and many comments and photos were quickly removed from mainland websites.
Protests in China are often quickly shut down or heavily controlled. It was not clear whether the organizers had permission to demonstrate Saturday.
The Chinese demonstrations appeared to be in response to online reports about a planned protest in Tokyo, where about 2,500 people held flags and marched near the Chinese Embassy to protest China's claim to the islands. Some also called for the release of Liu Xiaobo, the Nobel Peace Prize-winning Chinese dissident who is serving an 11-year prison sentence for subversion.
A spokesman for China's Foreign Ministry said China had contacted Japanese officials to "express serious concern" over the Tokyo protest, according to a statement on the ministry's website.
Spokesman Ma Zhaoxu made no mention of the anti-Japan protests in China _ a difference from last month, when the ministry responded to far smaller protests outside the Japanese Embassy in Beijing and the Japanese Consulate in Shanghai with a call for calm.
At the time, tensions were high over a collision between a Chinese fishing boat and two Japanese coast guard ships near the islands in the East China Sea. China repeatedly demanded the return of the detained fishing boat captain. Japan eventually released the captain, but Beijing shocked Tokyo by demanding an apology.
Earlier this month, the tensions seemed to calm after the prime ministers of the two countries held an impromptu after-dinner meeting in the corridor of an Asia-Europe summit.
Police in the Chinese cities of Chengdu, Xian and Zhengzhou would not confirm Saturday's protests, saying they would not talk to the media.
"It was peaceful, with no clashes," said an employee of a Starbucks next to the square in Chengdu where protesters gathered.
The man, surnamed Fu, said by phone that a large number of police had kept order and that the protest had ended.
In downtown Xian, a woman answering the telephone at the Bell Tower Hotel said crowds were still in the streets Saturday evening.
"It started in the early afternoon," the woman said. "There are still quite a lot of people here."
Associated Press Writer Eric Talmadge in Tokyo and researcher Henry Hou in Beijing contributed to this report.