The British government was in talks with Microsoft over backdoor access to the operating system, the BBC reported last month.
But Microsoft now stated it won't give governments such access to Windows Vista based computers.
"Microsoft has not and will not put 'backdoors' into Windows," a company representative said in a statement sent via e-mail.
The discussion centers on BitLocker Drive Encryption, a planned security feature for Vista, the update to the Windows operating system. BitLocker encrypts data to protect it if the computer is lost or stolen.
This feature could make it harder for law enforcement agencies to get access to data on seized computers.