SAN JOSE, Calif. -- Law enforcement officers led by the FBI arrested 27 people in a suspected software piracy ring that cost Microsoft Corp. and other companies hundreds of millions of dollars in lost sales.

FBI Director Robert Mueller said "Operation Cyberstorm" was one of several active federal investigations into software piracy. Software companies claim the problem is so widespread it costs the industry $12 billion a year.

Officials said the arrests followed a two-year investigation in which undercover officers, posing as distributors, purchased several million dollars worth of counterfeit software.

"It is one of the largest takedowns I think we have seen around the country," Mueller said Friday.

The 27 were arrested on a variety of charges, including money laundering, copyright infringement and trafficking in counterfeit goods, according to court filings.