Microsoft has filed 117 federal lawsuits against un-named defendants suspected of conducting illegal phishing scams.
The lawsuits, which were filed in the US District Court for the Western District of Washington in Seattle, accuses the "John Doe" defendants of using spam e-mail and pop-up ads to con consumers into disclosing financial information such as passwords, PIN numbers and account details.
In a statement, Microsoft says its legal team hopes to establish connections between phishing scams worldwide and uncover the largest-volume operators.
The company has also teamed with the US Federal Trade Commission (FTC)and National Consumers League (NCL) to raise consumer awareness of phishing scams. NCL says in little over a year phishing has become one of the top scams reported to its fraud information centre.
Aaron Kornblum, Internet safety enforcement attorney at Microsoft, says: "We must work together to stop these con artists from misusing the Internet as a tool for fraud."
In September last year Microsoft teamed with online retailer Amazon to file a joint lawsuit against a Canadian firm accused of sending out spam e-mail from spoof Amazon and Hotmail addresses.