Police in Qingdao, Shandong province took six suspects into custody on allegations of robbery, provocation and arson during a protest against Japan's "purchase" of China's Diaoyu Islands.

A suspect surnamed Qi was caught by police on the morning of Sept 15 while he was robbing digital cameras and shoes from a Japanese-funded supermarket in Huangdao district, the Qingdao public security bureau said on Sept 19.

Qi also smashed the counter and some commodities in the supermarket during the protest, said the notice.

Another four suspects were caught when they destroyed vehicles with weapons in two Japanese auto sales stores on the afternoon of Sept 15.

In another case, a man surnamed Chen set plastic and paper on fire in front of a Japanese factory in Huangdao district. He was caught by police when setting a car on fire in a Japanese auto store. He was taken into custody with on the allegation of arson, said the notice.