More than 10,000 anti-Japanese protesters on Saturday hurled rocks, bottles and eggs and shouted abuse at the Japanese embassy and the residence of the Japanese ambassador.
The protests were the largest in Beijing since about 10,000 members of the banned spiritual group Falungong encircled the Communist Party's leadership compound in July 1999.
Even though protesters were seen marching on Beijing's main thoroughfare, Changan Boulevard, and the protests caused traffic jams, the city's major newspapers such as the Beijing Morning Post and Beijing News carried no reports about the event.
A staff member contacted at the Beijing Morning Post on Sunday said she did not know why such a large protest was not covered. Editors of other newspapers could not be reached for comment.
The only mention of the protests was on internet websites specifically set up by anti-Japanese groups. These contained comments and pictures.
The Chinese government routinely censors news it considers too sensitive.
Although the protests appeared to have been approved by the government, authorities fear that even government-sanctioned protests could get out of hand if too many people find out about them and want to participate.
The police tightly manage such protests. Demonstrators condemned Japan for its handling of its wartime past and its pursuit of a permanent seat on the UN Security Council, amid mounting tension between the countries.