The US has urged China to investigate reports that indicate China redirected internet traffic and used information for attacking American websites.
US State Department spokesman Jeff Rathke was quoted by Reuters as saying, "We are concerned by reports that China has used a new cyber capability to interfere with the ability of worldwide Internet users to access content hosted outside of China.
"The cyber attack manipulated international web traffic intended for one of China’s biggest web services companies and turned it into malicious traffic directed at U.S. Sites."
The Chinese government has denied the claims and has said it was not involved in the hacking.
An analysis by Citizen Lab of Toronto found that Beijing uses the Great Cannon cyber attack programme for hacking individual IP addresses, targeting foreign computers that are linked with China based websites.
Cylance senior security researcher Justin Clarke said: "The Great Cannon is one of the biggest cyber weapons that has become publicly known.
"Every user in China could be potentially weaponized by their government," he said.
China has recently upgraded the Great Firewall website-blocking systems that will give the country increased control over domestic internet use.