BlackBerry maker Research In Motion reported a 58 percent jump in quarterly profit on Thursday, as sturdy demand from holiday shoppers helped fend off growing competition, sending its shares sharply higher.

Profit rose to $628.4 million, or $1.10 a share, in its third quarter ended November 28, from $396.3 million, or 69 cents, a year earlier.

Revenue increased 41 percent to $3.92 billion.

The results topped analysts' expectations for a profit of $1.04 a share and revenue of $3.78 billion, according to Thomson Reuters I/B/E/S.

RIM, which faces growing competition from such devices as Apple's iPhone and Motorola's Droid, added about 4.4 million subscribers in the quarter, for a total of about 36 million customers.

Waterloo, Ontario-based RIM forecast fourth-quarter earnings per share of $1.23 to $1.31, revenue of $4.2 billion to $4.4 billion. It sees gross margin of about 43.5 percent and expects to add 4.4 million to 4.7 million new subscribers..

Before RIM issued that forecast, analysts had expected earnings per share of $1.12 and revenue of $4.1 billion.

RIM shares jumped 12.2 percent to $71.20 in extended trading on Thursday.

($1=$1.07 Canadian)

(Reporting by Susan Taylor; Editing by Frank McGurty)