Specifically, he said Redmond cut the amount of time given for compatibility testing with the new OS from two months to six days.
As a result Windows-10 users are being warned by the operating system to just use Microsoft apps, or applications from Redmond's store - where the software giant can take a cut of any sales.
In addition, when Microsoft users install Windows 10, the operating system shuts down security suites and runs its own anti-malware Defender tool instead if the suites are deemed incompatible.
Anatoly Golomolzin, deputy FAS head, said that the short period of time given to software makers, and the fact that Microsoft has its own security suite, gave Redmond "unjustified advantages," and as such his agency would be probing the matter.
Eugene Kaspersky made other claims about Microsoft's Windows-10:
Even if you turn Defender off it will occasionally fire itself up and display results to the user to encourage a change of supplier.
Microsoft had no comment at time of going to press.