Microsoft has announced that it has freed over 4.7 million infected personal computers from control of hackers in its most successful digital crime operation ever.

The largest software maker in the world also said another 4.7 million machines are still infected, many of which are likely controlled by cybercriminals, Microsoft's Digital Crimes Unit said on July 10.

Locations with the largest amount of infected machines includes: India, Pakistan, Egypt, Brazil, Algeria, and Mexico.

Richard Domingues Boscovich, assistant general counsel of the unit, said Microsoft gave government authorities and Internet service providers IP addresses of infected machines so that they could start helping users remove the viruses.

"Those victims are currently not aware they are infected," Boscovich said, according to Reuters.

Boscovich added that the operation is the most successful of the 10 launched by Microsoft's Digital Crimes Unit to date.

Microsoft was able to find the compromised PCs by intercepting traffic headed to servers at Reno, Nevada-based Vitalwerks Internet Solutions, which was used by criminals to communicate with compromised PCs through free accounts on its No-IP.com services.

Vitalwerks isn't happy with the way Microsoft handled the operation, claiming some 1.8 million of its users lost service for several days.

The firm said it would have been happy to help Microsoft, without interrupting service to legit users.

Microsoft has since apologized, saying that the disruption occurred because of a "technical error." Its service has since been restored.

The operation began back on June 30, according to Reuters. It targeted malicious software known as Bladabindi and Jenxcus, which Microsoft claims works in similar ways and were written and distributed by developers in Algeria and Kuwait.

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