Toronto, Dec 24 - A rare service breakdown left millions of BlackBerry users across North America without service for hours this week.

In a statement Wednesday, BlackBerry maker Research in Motion (RIM) said the service blackout was caused by a bug in its newly installed instant messaging system.

A flaw in the two versions of the BlackBerry instant messaging system was responsible for the service breakdown, said the wireless giant which is based at Waterloo near Toronto. The blackout lasted eight hours, beginning Tuesday night when e-mail service on the BlackBerry devices stopped working.

Though email service was back by early Wednesday morning, users reported a lag in sending and receiving emails and web browsing.

A similar e-mail blackout was reported across North America early last Thursday. It was rectified by mid-afternoon.

"Root cause is currently under review, but based on preliminary analysis, it currently appears that the issue stemmed from a flaw in two recently released versions of BlackBerry Messenger (versions 5.0.0.55 and 5.0.0.56) that caused an unanticipated database issue within the BlackBerry infrastructure," the BlackBerry maker told the local media outlets in an email.

"RIM has taken corrective action to restore service," the Canadian company said.

The BlackBerry maker had made the two versions available for download December 14.

Apologising for the blackout, RIM advised those who have downloaded these versions to upgrade the application as a precaution.

Blackouts on the Blackberry are rare. The last outage in North America, which lasted many hours and was blamed on a system upgrade, was reported in February 2008. (IANS)