Microsoft chief executive Steve Ballmer announced Tuesday that the US software giant's Bing search engine and maps would be the default service on BlackBerry devices.

Ballmer made the announcement during a surprise appearance at the three-day BlackBerry World developers conference being held by BlackBerry maker Research in Motion (RIM) in Orlando, Florida.

"Microsoft CEO Steve Ballmer announces Bing as default search and map application solution for BlackBerry devices," RIM said in a statement on its Twitter feed.

Google dominates the Internet search space but Microsoft is mounting a challenge and they are battling over the rapidly growing market for mobile devices.

RIM lowered its quarterly earnings outlook last week on weaker BlackBerry sales as it faces stiff competition from the iPhone and handsets running Google's Android software.

Finland's Nokia announced in February that it planned to begin using Microsoft's Windows Phone operating system for its smartphones.