Microsoft has released an update to its Windows Genuine Advantage notifications programme.

The software giant had come under fire earlier this month because the anti-piracy tool checked in with Microsoft every time users booted up their systems. It prompted privacy watchdogs to describe the tool as 'spyware'. 

Microsoft promised to change the frequency of the check-in to every 14 days. Tuesday's update instructs the validation tool to check in only after it has been updated.

Microsoft said that the initial check-in frequency was part of a pilot which has now been completed.

The tool collects information about a system's configuration including make and model, regional settings, product keys, a Global Unique Identifier as well as the name and revision number of the system's Bios and hard drive serial number.

The company logs a user's IP address on check-in with the Microsoft server.

Microsoft has been pushing the tool as an important security update through its automated update services.

The tool is required for users seeking to download non-security updates and free applications from the Microsoft website, but is optional for downloading security updates.

Microsoft published a Knowledge Base article on Tuesday with instructions on how to remove the WGA tool.