Microsoft Corp. on Tuesday launched a new offensive against the so-called "cybersquatters," who allegedly earn pay-per-click profits from advertising on thousands of websites including Microsoft's.

The software giant said cybersquatters and the "typosquatters," namely people who register web addresses either with trademarked terms or with common misspellings in the hope of luring web surfers, are now registering more than 2,000 domains each day targeting Microsoft.

Microsoft filed three lawsuits in U.S. federal courts this week claiming that some website operators have registered and operated hundreds of domain names with the sole purpose of reaping "bad faith" profits and in violation of laws.

Two of the complaints, filed in Utah and California, named known individuals accused of running more than 400 such sites. A third "John Doe" complaint is aimed at unmasking alleged cybersquatters, affiliated with 217 different domain names, who have paid privacy protection services to have their registration information shielded.

The vast majority of these sites, with addresses like "microsoftrebate.com," "xbox36com.com" and "msnfinance.com," are bought by professional domain operations that place pay-per-click advertisements on the pages, Microsoft said. About a quarter of the sites use privacy services to disguise their identities.

"Microsoft has witnessed a virtual land rush for Internet domain names with the goal of driving traffic for profit," Aaron Kornblum, the company's Internet Safety Enforcement attorney said.

The litigation marks the first time Microsoft has filed lawsuits stemming exclusively from a 1999 law called the Anticybersquatting Consumer Protection Act, or ACPA, which subjects anyone who "registers, traffics in or uses a domain name that is identical to, confusingly similar to "an existing trademark to up to 100,000 dollars in damages.

The company also announced plans to expand its crackdown on resale of such domain names on Internet auction sites.

Microsoft noticed the surge in sites earlier this year during its efforts to monitor so-called phishing sites, which mimic bank and other sites as part of identity-theft schemes.

The company also found squatter sites with more sinister purposes than collecting dollars, which included distributing malicious software and exposing minors looking for children's sites to pornography, according to Kornblum.