Blackberry founder Mike Laziridis says service 'is improving'

Blackberry's owner RIM has said that services are gradually returning to normal, following a three-day global blackout.

Millions of customers worldwide had their messaging and email service disrupted with many turning to Twitter to express their anger.

In a video message on the company website, RIM Founder and Co-CEO, Mike Lazaridis, gave no date for when a full service would be restored.

He also warned that there could be more instabilities to come.