Most of the viruses spreading across the Internet in China are the work of just 10 illegal but highly sophisticated groups, according to a report by Beijing-based Kingsoft Co.

The report said that more than 30 groups are in fierce competition for a share in the underground virus market, where customers pay the groups to produce and spread the viruses. But it said just 10 had control of 80 percent of the market.

The groups can introduce the viruses either by hacking into websites or by establishing a business partnership with those in control of the sites and sharing the income generated, it said.

The groups make their money by installing the viruses in popular websites offering free downloads of movies, e-books and video games, obtaining computer users' financial details and causing them great economic losses, said the report.

The hacking groups are believed to be making huge amounts of money from the business with the report saying that just one group could cash in to the tune of at least 150 million yuan (US$22.8 million) a year.

An official with Kingsoft surnamed Ge said the company was seeking help from police in tracking down the hackers.

Meanwhile, a Shanghai Daily investigation has discovered that one such group is using the website www.xwoditg.cc to sell its self-developed cell phone wiretap virus. The virus, called X-spy, has already infected 150,000 cell phone users across the country, according to report from another anti-virus company, NetQin Co.

Although the virus has been listed as spy software and was banned from sale in China years ago, the website and the company have relocated to Thailand to continue their business.

Vendors boast that the virus can allow owners to listen to other people's conversations by using a loophole in smartphone systems.

They said the virus could either be installed manually on the target's phone or hidden in a multimedia message send to the phone.

Once installed, each call to the target phone can be listed to by the virus owner.

"One suggestion is that you deliberately break the target's phone and send another one with the virus to him/her, then you will take control of every secret," one vendor said.

Vendors promote their product by saying that it could save people's marriages with wives able to know exactly what their husband is up to or if he had a mistress and help parents gain control over their children as they would know every detail of their movement from their phone conversations.

Such software costs from 1,680 yuan to 9,880 yuan.

An official with the government department responsible for China's computer network security said yesterday they were looking into the case.