Websites of Chinese nationalist groups were blocked Friday as the government tried to forestall anti-Japanese protests ahead of a sensitive political anniversary.
Ever-present anti-Japanese sentiment in China has been inflamed in recent weeks by Japan's seizure of a Chinese fishing boat in waters near an island group north of Taiwan that is claimed by both Tokyo and Beijing.
China has protested over the incident and demanded the return of the ship's captain, who is being held by Japan and could face prosecution for obstructing the coast guards' public duties. The boat was seized after it ignored demands to leave the area and collided with two Japanese patrol boats.
On Friday, the website of the China Federation for Defending Diaoyutai was taken offline, and messages about organizing protests over the incident were scrubbed from Internet bulletin boards. Diaoyutai is the Chinese name for the disputed islands, referred to by Japan as the Senkakus.
Federation organizer Li Nan said he did not know who was responsible for the website's takedown, although Chinese authorities tightly monitor the Internet and regularly censor content deemed subversive.
"There are rumors that our federation is organizing a protest. Actually we are not. And we issued a statement denying it," Li said.
Before being taken offline, the federation's website had posted a statement condemning Japanese media reports of alleged protests planned for Saturday.
Saturday marks the anniversary of the 1931 ``Mukden Incident'' that led to the Japanese occupation of China's northeast. The date has in the past been marked by official commemorations and scattered anti-Japanese protests in China.
Meanwhile, in Chinese-administered Hong Kong, 10 people marched from a nearby post office to the downtown building housing the Japanese consulate demanding the release of the ship's captain.
The protesters chanted ``Down with Japanese militarism'' and ``Japan Get out of Diaoyutai!'' They left peacefully after delivering a list of their demands to a representative from the consulate.
While China's ruling Communist Party partly encourages anti-Japanese sentiment to burnish its nationalist credentials, it remains obsessed with social stability and suspicious of any independent movement that could spin out of control and challenge its authority.
Beijing has stated that the arrest of the fishing captain could damage its relations with Japan and has summoned Japan's ambassador to China, Uichiro Niwa, five times.
Last week, it postponed talks with Japan on contested undersea gas deposits in the East China Sea that would have been the second meeting over exploration in the area.
Japanese official Katsuya Okada said Friday that China had shipped equipment to an offshore platform in the disputed gas field, Japan's Kyodo News Agency reported. So far, neither China nor Japan has begun extracting gas from the field in keeping with a two-year-old agreement.
Japan in January warned China that it would take unspecified countermeasures if China were to begin extracting gas from the field.
On Sept. 18, 1931, Japan's military attacked the northeastern city of Shenyang, then known as Mukden, leading to the Japanese occupation of China's northeast. That was followed in 1937 by the occupation of much of China that lasted until Tokyo's 1945 surrender at the end of World War II.