Research In Motion said on Wednesday it was working to end a three-day global disruption of BlackBerry services that has frustrated millions of smartphone users and put more pressure on the company for sweeping changes.

The Canadian company, in a hastily announced conference call, did not say when it would fully restore service to the tens of millions of customers who have been affected. But it said it found no evidence that hacking or a system breach caused the outage, which has affected email and instant messaging services on five continents.

Our priority is to get the service up and running, because at the end of the day what's going to make our customers happy is to have their BlackBerrys working again, David Yach, RIM's chief technology officer for software, said during the call.

Shares of RIM were down 3.9 percent in Toronto trade after the late-afternoon call, which RIM held days after the disruptions began in Europe, the Middle East, Africa and India. The outage later spread to the Americas.

The disruption, the worst since an outage swept North America two years ago, is likely to fuel calls for a management shake-up and a possible sale or split of the company, which has failed to keep pace with Apple and other rivals in a rapidly changing market.

The troubles could damage RIM's once-sterling reputation for secure and reliable message delivery and risks a further devaluation of its proprietary BlackBerry offering.

RIM's system, unlike those used by other handset makers, compresses and encrypts data before pushing it to BlackBerry devices via carrier networks.

(Reporting by Alastair Sharp; additional reporting by Euan Rocha and Pav Jordan)