It was business as usual here as the weekend marking the first anniversary of massive anti-Japan demonstrations got under way, with no rallies and no major upgrading of security.

The only sign security was tighter than usual at the Japanese Embassy, one of the targets of attack during the protest last April 9, was a security van parked in front.

"We have not received reports of anything out of the ordinary happening, either in Beijing or in other parts of the country," an embassy official said.

The embassy was not taking any special steps over the weekend, the official said.

The first demonstrations last year began in early April in the central city of Chengdu and southern city of Shenzhen, to oppose Japan's bid for a U.N. Security Council seat and the country's treatment of its wartime history.

The April 9 demonstration in Beijing began in the city's university and high-tech district and spread across town, picking up sympathizers as it reached the Japanese Embassy.

Some of the demonstrators pelted the embassy and the ambassador's residence with rocks and water bottles, while others attacked Japanese restaurants.

The rallies spread to other cities, including Shanghai, later in the month. Authorities publicly forbade further demonstrations in late April, amid protests from Japan and what analysts suspect was possible fear that the rallies could turn on the Chinese government.