Microsoft will start updating the Mango OS for its Windows Phone in a "week or two" according to a senior staffer.

Brandon Watson who is in charge of apps and developers on the Windows Phone confirmed the upgrade in a tweet.

"Boom... no more rumours. Mango to start rolling out on Windows Phone in just a week or two", tweeted Watson.

The new upgraded OS will bring a number of improvements to the existing system including more locations and languages that Windows Phone can support worldwide.

The timing also marks the imminent launch of Nokia phones that carry the Windows Phone OS. Nokia is planning to release smartphones with just the Windows OS, killing off its Symbian platform and refusing Google's Android OS. The first Nokia Windows Phone is expected to launch at the Nokia World show in London on October 22.

"For months, we and dozens of our partner companies have been laying the groundwork for the Windows Phone 7.5 update - and making solid progress. As a result, we now expect to start rolling it out in the next week or two," wrote Eric Hautata, the general manager for customer experience engineering in the Windows Phone division.

He advised impatient users against installing any unauthorized copies of the software claiming that the leaked copies can disrupt the phone's operation.

"During the official Windows Phone 7.5 update process, every Windows Phone will also receive software from the handset manufacturer," he said. "This matched and paired firmware has been painstakingly tuned so your phone - and apps - work with all the new features of Windows Phone 7.5. Since your phone requires the proper firmware to function as designed, my advice is simple: steer clear of bootleg updates and homebrew tools."

Windows Phone has been trying to get a slice of the competitive smartphone market since it was released in October 2010 but has been outperformed by market leaders Apple and Google's Android. The partnership with Nokia and the revamped OS could potentially take the lead from Apple and Google.