Symantec is suing what it claims is a software piracy ring, in operation in North America since late 2003.

The lawsuit was filed in Los Angeles and seeks more than $15 million in damages from a network of US and Canadian businesses that it says have sold counterfeit versions of Symantec's products, including Norton AntiVirus, pcAnywhere and Veritas Backup Exec.

The businesses, which operated under eight different names, including Sili, Advanced Sales Productivity Solutions and GT Micro, used spam and online advertising to offer Symantec's software at cut-rate prices, said a Symantec spokesman.

Customers who paid for the software would then be sent disks with Symantec's logo, wrapped in plain white sleeves. The disks, which came without documentation, would not install or work properly and could also include malicious software that would then be used to steal sensitive information from the purchaser's computer, Paden said.

Symantec began investigating the matter in early 2004, when it started receiving complaints from customers who had bought the bad software, Paden added. "The people who bought these disks thinking they were from Symantec would come to our customer service," he said.

One of the Sili websites named in Symantec's complaint, Sle-business.com, offers $6-per-user volume licensing deals on Symantec's Norton AntiVirus 2006. That product typically sells for about $20.

Sle-business.com's website also offers software from McAfee, Intuit, Corel and Webroot, among others. Sili representatives could not be reached immediately for comment.

Symantec has worked with police to seize more than 100,000 copies of counterfeit disks, but the spokesman did not know if criminal charges would be forthcoming in the case. "We are working with law enforcement," he said. "I can't tell you who because if I did that would tip our hands to the extent of our investigation."

Like many other vendors, Symantec has become more aggressive in its fight against unauthorised copying. In 2002, Symantec claimed it was losing about $500 million per year to software piracy, but says it has now reduced those losses to less than $50 million per year.