A report in the Financial Times said Google was phasing out the internal use of the operating system because of security concerns. It attributed the claim to "several" Google employees.
According to the Financial Times, the directive to move to other operating systems began in January, after Google said it was hacked.
"We're always working to improve the efficiency of our business, but we are not going to comment on specific operational matters," Google Australia said in a statement to ZDNet Australia when asked if there was any truth in the report and whether the company had been asking employees to switch from Windows because of security concerns.
Asked for further comment, Google's Australian office said: "Sorry, we're not commenting on that".
On a worldwide basis, Google employed 20,621 full-time employees as of 31 March 2010, according to its first quarter 2010 financial results.
Microsoft Australia has been contacted for comment and we will update this story when we receive a response.