Symantec has filed suit against an alleged software piracy ring in operation in North America since late 2003, the software vendor claims.

The lawsuit, filed last month in US District Court in Los Angeles seeks more than $15 million (£10.08m) in damages from a network of US and Canadian businesses that are alleged to have sold counterfeit versions of Symantec's security products, including Norton AntiVirus, pcAnywhere and Veritas Backup Exec.

These companies and their affiliates run a global counterfeit organisation, Symantec said. 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 Cris Paden, 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 also offers software from McAfee, Intuit, Corel and Webroot Software, 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 Paden 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 was losing about $500m per year to software piracy, but it has now reduced those losses to less than $50m per year, he said.

Customers who are worried that they may be buying counterfeit software online should make sure they are actually giving their credit-card information over a secure website, Paden said. That means that when they are asked to enter a credit-card number, the Web address should begin with https://, and there should be a locked padlock displayed near the address to indicate that the browser is visiting a secure site.

"That's the smoking gun as to whether you're dealing with a legitimate outfit or not," Paden said. "99 percent of the time these guys don't use this."