Credit: Peter Cade/Iconica/Getty Images

ABC News' Scott Goldberg reports:

The Federal Trade Commission announced a worldwide crackdown on firms running bogus technical support scams that targeted victims in the U.S. and five other countries.

"These scam artists we're talking about today have taken 'scareware' to a new level," said FTC Chairman Jon Leibowitz, who estimates the schemes have cost consumers "tens of millions of dollars."

The FTC said six operations based in India posed as legitimate computer companies, such as Microsoft or Symantec, and convinced people to use their credit cards to pay as much as $450 to fix problems that didn't even exist.

So-called representatives from the phony companies used technology to disguise their phone numbers, making it look as if they were calling from the same countries as their victims. The "representatives" claimed to have found viruses on the users' home computers. Leibowitz said the callers would point users to a standard Microsoft warning message and claim it was a virus posing a serious threat to their computers.

The FTC said a trustworthy computer company would never "cold call" computer users, and anyone who receives this type of call should hang up.

Although the exact number of victims stung by these scams is not yet known, the FTC said it received 2,400 complaints from the U.S. alone. The callers also targeted computer users in Canada, Australia, Ireland, New Zealand and the U.K..

As part of the crackdown, Leibowitz said the FTC got a federal restraining order that froze the assets of the six operations in India, and shut down the phone numbers that were used to make the calls.

Leibowitz emphasized that the FTC was not a law-enforcement agency and didn'tt have the power to make arrests.

For more information visit: www.onguardonline.gov.