The Yasukuni Shrine Web site has been under attack from hackers since September, a shrine official said Thursday.

The shrine posted a notice about the attacks on the Web site Wednesday, explaining the countermeasures taken to deal with the situation.

The attacks apparently have been originating in China, where the shrine is a popular cause of resentment because it honors Japan's war dead as well as Class-A war criminals from World War II.

Facing up to 15,000 hits per second since Sept. 3, the site occasionally has been difficult for browsers to access. It experienced concentrated attacks lasting more than one hour on five occasions last year, the official said.

The notice posted on the site said Chinese-language spam carrying a virus and using the shrine's e-mail address as the sender was sent in massive numbers to third parties on Sept. 21, infecting many computers on the receiving end. Some of the e-mails were found to have been sent using a Chinese mail server.

The bulk of the denial of access attacks followed the posting of a message on an Internet bulletin board based in China in late December that revealed data concerning the Yasukuni site and urged readers to attack it, according to the notice.

The shrine said it has taken steps in cooperation with police and other authorities to build a system to protect its Web site from the attacks.

Similar attacks on the site have occurred on and off since Prime Minister Junichiro Koizumi began making annual visits to the Shinto shrine in August 2001.

The visits have triggered criticism and protests from other parts of Asia, especially China and South Korea, which were victims of Japan's military aggression.

They say the visits glorify Japan's militaristic past.