TORONTO - Shares of Research In Motion (TSX:RIM) were ahead six per cent in afternoon trading as investors reacted to the BlackBerry maker's surprise increase in subscriber numbers.

The Waterloo, Ont.-based company's stock rose 41 cents to $6.91 on the Toronto Stock Exchange.

The move higher followed comments from RIM's chief executive Thorsten Heins on Tuesday.

He told the audience at a developer conference in Silicon Valley that RIM has grown its user base to about 80 million at the end of its second quarter.

That's up from 78 million in the previous quarter.

RIM is scheduled to report its second-quarter financial results on Thursday after market close.