Recent legal action against software pirates operating on eBay has scared counterfeiters away from the auction site, it was claimed today.

The Software & Information Industry Association (SIIA) said that lawsuits filed against three sets of pirates have had a "discernable impact" on the number of illegal auctions posted on eBay.

The SIIA tracked the incidence of auctions selling illegal copies of 18 software products for 30 days after its legal offensive.

Depending on the product, there was a 20-50 per cent decrease in total auctions placed in the first week or two following the announcement.

"The SIIA and its members are very pleased to see that our actions have made a measurable dent in the number of illegal auctions of software," said SIIA president Ken Wasch.

"We expected that illegal postings would drop right after the arrest announcements, but are happy that the level of infringing auctions has remained below the baseline since then."

The SIIA added that it plans to continue its lawsuits against illegal auctions in the months to come.

"These are not prosecutions of ordinary people selling off old software. These are professional criminals making millions of dollars from unsuspecting consumers," said Keith Kupferschmid, vice president of intellectual property policy and enforcement at the SIIA.