China's Supreme Court and prosecutors office will step up the fight against computer hacking by toughening penalties for those caught doing it, state media said on Monday.

Under rules coming into effect from Sept. 1, people who knowingly purchase, sell or cover-up illegally obtained data or network control will be subject to criminal penalties, the official Xinhua news agency cited a statement as saying.

Such activities have become increasingly unrestrained, even giving rise to large online transaction platforms. Penalizing these violations helps sever the profit chain of hacking and other related crimes, it added.

While the United States says many hacking attacks appear to come from China, often targeting human rights groups as well as U.S. companies, China says that it is one of the world's biggest victims of hacking attacks.

A crime endangering information network security poses a threat not only to network security but also to national security and public interests, the news agency said, adding that the new rules were aimed at cracking down on such crimes with greater force.

In 2009, more than 42,000 Chinese websites were distorted by hackers, Xinhua said.

Data from the Ministry of Public Security shows that the number of viruses circulating on the internet has surged 80 percent from a year earlier in the past five years, Xinhua said. The ministry also estimates that eight out of 10 internet-connected computers are controlled by hackers, it added.

In its annual report to the U.S. Congress on China's military last Wednesday, the Pentagon warned that hacking attacks from China could one day be used for overt military means, rather than just trying to access data.

Last week, footage emerged online of a brief clip on Chinese state television of purported cyber hacking attacks launched by the country's military, despite long-standing official denials that the government engages in such activity.

Google , the world's largest search engine, partially pulled out of China last year after concerns of censorship and a serious hacking episode.

Google, who said the attacks originated from China, was one of the dozens of high profile companies targeted in an ultra-sophisticated cyberattack named Operation Aurora that took place in the second half of 2009. Yahoo , Adobe and Dow Chemical were also reportedly among the targets.