Nokia has started deliveries of its new top-of-the-range model N900, a key product for the world's top phone maker in its battle against rivals iPhone and Blackberry.

Nokia Chief Executive Olli-Pekka Kallasvuo said in a speech the company started deliveries of the phone on Tuesday.

The N900 model is Nokia's first phone running the Linux Maemo operating system, which analysts see as a key for Nokia to regain ground in the coming years.

Nokia has kept its overall market share stable, close to 40 percent, but it has lost share among more expensive models to the likes of Apple and RIM.

High-end products are important for Nokia because the company has not only lost market share there, but its average selling prices have declined faster than the industry average.

Goldman Sachs has said it expects Nokia's value share -- a measure reflecting average prices and underlying market share -- for phones costing more than $350 to decline to 13 percent this year from 33 percent just two years before.

(Reporting by Brett Young; Writing by Tarmo Virki; Editing by Erica Billingham)