Nokia now ships half of the world's smartphones, according to figures released by analyst firm Canalys.

The handset giant shipped over five million smartphones in the first quarter of 2005, nearly doubling its market share on this time last year.

The launch of new phones like the 9500 Communicator and the 9300 clamshell helped propel Nokia to the top spot.

"The keyboard-based models are important products in Nokia's push to become the preferred device supplier for enterprise mobility," said Chris Jones, Canalys director and senior analyst.

"But both were in development prior to the formation of Nokia's Enterprise Solutions Group, and we expect to see it bring many more business-class smartphones to market over the coming quarters.

"With demand among businesses for sophisticated mobile email growing rapidly, all vendors need to consider how they will address this need, not only in terms of device design and software integration, but in their routes to market."

There was also good news for Research in Motion, which builds the BlackBerry email client. Sales rose 100 per cent year on year, leaving it in third place behind PalmOne.

In the operating system stakes Symbian now accounts for nearly two thirds of all smartphones. Microsoft is in second place with 18 per cent, while PalmSource lost ground to capture just over 10 per cent of the market.

More worrying for the Palm camp is the limited geography of the Palm platform. The US now accounts for 80 per cent of revenues, and the operating system has yet to achieve serious penetration in the European and Asian markets.