Microsoft Corp launched an update of its Windows phone software on Tuesday, hoping a host of new features will help it close the gap on smartphone leaders Google Inc and Apple Inc.

The updated software, code-named Mango, will appear on new Windows phones beginning this autumn, and be available for existing Windows phone users before that, although Microsoft has not set a timetable for making the update available.

Microsoft said the update involved 500 new features, including Internet Explorer 9 as the mobile browser, Twitter and LinkedIn feeds integrated into contact cards, automated Facebook check-ins, and access to more than 17,000 downloadable applications.

Microsoft is banking on the new version of its phone software to get its recent alliance with Nokia off to a strong start. The first phones made by Nokia using Windows software are expected late this year or early in 2012.

The two have some work to do to catch up with Google's Android, which now runs 36 percent of smartphones sold globally, followed by Apple with 17 percent, according to research firm Gartner.

Last quarter, Microsoft held only 4 percent of the smartphone operating system market, but was looking to convert the 27 percent market share held by Nokia's Symbian, which will be replaced by the Windows system in most of Nokia's new phones.

(Reporting by Bill Rigby, editing by Maureen Bavdek)

Apple inc. Microsoft Smartphone Update