Microsoft belatedly learned that 'Metro' has been prior registered to a different entity and therefore cannot be used with the tech giant's marketing of the upcoming Windows 8, reports said.

Tech blog site The Verge has reported of an e-mail advisory that it claimed Microsoft sent to company employees and its partner developers. The meat of the mail: Drop the Metro term in any mention of Microsoft's new operating system, which it touted as the biggest revamp of its core product in more than a decade.

Another blog site, Australia-based Bit News also reported on the alleged existence of such notice from Microsoft, which came barely two weeks as the tech giant prepares to roll out the final version of Windows 8 to app developers.

Microsoft had announced last week that it will unleash the Windows 8 RTM to developers beginning August 15, setting off the official countdown for its commercial debut, which the software maker said will definitely occur on October 26.

The company has been harping that one of Windows 8's distinct features is the tiled collection of apps on the operating system's start screen, which was christened Metro.

It turned out, however, that legal questions will prevent Microsoft from actually using the term, which blog reports suggested was actually a trademark exclusively owned by Metro AG.

According to The Verge, Metro AG is based in Germany, quickly clarifying too that Microsoft has yet to confirm if the German entity was actually the stumbling for it to capitalise on the Metro branding.

Microsoft merely advised its partners that the label will not be a part of the Windows 8 package pending "discussions with an important European partner."

The nature of the talks was still under wraps, reports said, and Microsoft has so far withheld information if it was pursuing to acquire the name Metro from its legal owners or if it was settling a legal dispute with Metro AG, if there was one.

For the time being, Microsoft informed its partners that in lieu of Metro, the new OS interface can be referred as Windows Phone or simply Windows 8.

The shift, according to ZDNet, was explained by Microsoft as merely a way of promoting its own brand names that is more familiar to global users.

"We have used Metro style as a code name during the product development cycle across many of our product lines. As we get closer to launch and transition from industry dialog to a broad consumer dialog we will use our commercial names," the tech news site reported Microsoft as saying in a statement.

Also, SmartCompany reported on Monday that Metro will eventually be ditched as a component of Windows 8's in favour of a replacement term that the tech titan said should be finalised by the end of the week.

While a minor glitch, tech watchers lamented the news of Metro's dropping from the Windows 8's rolls, which they hope would be substituted by something that would easily rub on the way Metro did.