Earlier this afternoon, BlackBerry issued the following statement via their official Facebook page about the cause of the outage:
"The messaging and browsing delays being experienced by BlackBerry users in Europe, the Middle East, Africa, India, Brazil, Chile and Argentina were caused by a core switch failure within RIM's infrastructure. Although the system is designed to failover to a back-up switch, the failover did not function as previously tested. As a result, a large backlog of data was generated, and we are now working to clear that backlog and restore normal service as quickly as possible. We apologize for any inconvenience, and we will continue to keep you informed."
Some reports have suggested the EMEA outage could be fixed by 8am BST/3am EST which hopefully could be the end of the outage worldwide.