Japanese authorities have claimed a number of cyber attacks on its financial sector and other institutions are a retaliation from China over a land dispute.
The websites of 19 Japanese banks were made temporarily unavailable following cyber attacks originating from China, according to Japan's National Police Agency, which claimed that many of the targets had been named on hacking group sites.
Other organisations such as the Tokyo Institute of Technology said that they had been targeted which resulted in the theft of personal data, as well as other government departments also targeted in distributed denial of service (DDOS) attacks.
Some websites were altered - with a picture of the Chinese flag appearing on one site - according to the Japanese Times. The attacks are believed to have ceased, though Japanese authorities are warning organisations to take precautions against further threats.
The attacks are believed to be protesting the nationalisation of islands in the East China Sea, Diaoyu and Senaku, which were previously privately owned.
The move by the Japanese government to purchase the resource rich islands has sparked outrage in China and has led to a wave of anti-Japan protests.
Such protests have caused a number of Japanese firms operating in China to suspend factor production. Panasonic was one of the companies which chose to temporarily suspend production this week, claiming that workers in its Chinese component factories had "sabotaged" its operations.