The Canadian firm reported revenues of $211m (�115m) for the last three months of 2003 - up from $87.5m year-on-year - with net profits up 150% to $41.5m.

The Blackberry became a technology icon in the late 1990s as a tool that delivered e-mail automatically to executives on the move.

But it now faces tough competition from a profusion of rival wireless devices.

User growth

RIM is now planning to license its technology for use on other companies' equipment as well as selling its own devices.

Despite the competition, RIM's subscriber base is growing fast.

The firm said it gained 204,000 new users during the quarter, taking the worldwide total to more than 1 million.

Its share price - $105 - is so high that it is splitting its shares, giving two new shares for each old one so as to increase liquidity.

High price

But some investors are concerned the price has shot up too fast, particularly given concerns about the mobile phone market reflected in disappointing figures for Nokia earlier this week.

One measure of whether a share price accurately reflects the company's worth is the price-to-earnings ratio.

This divides the share price by the profit per share, with fairly priced non-technology stocks usually hovering somewhere between 10 and 20.

In RIM's case, this comes to more than 200 - high even by late-1990s tech stock standards.