China is one of the world's biggest victims of cyber attacks, and Chinese companies should improve their Internet security systems and remain vigilant to cyber threats, Internet security researchers said

At least 60 percent of the attacks targeting China's large companies, government, and scientific research institutions come from overseas, according to Liu Siyu, director of the security research team at Web security company Beijing Rising Information Technology Co Ltd.

Major sources of the attacks include the United States, South Korea, Japan and India, according to a report released by Rising on the cyber security situation in 2012.