Research In Motion defended its PlayBook tablet computer against charges its battery life is shorter than that of rivals already on the market.

"Any testing or observation of battery life to date by anyone outside of RIM would have been performed using pre-beta units that were built without power management implemented," the BlackBerry maker said in an emailed statement with Reuters.

Kaufman Bros analyst Shaw Wu earlier this week cited unnamed sources saying the PlayBook's battery lasts "a few hours" compared with six hours for Samsung's Galaxy Tab and 10 hours for Apple's iPad.

Wu said RIM may have been forced to delay the PlayBook's launch so it could re-engineer the product.

The Playbook is due to be released early in 2011.