BlackBerry maker Research in Motion (RIM) claims a "core switch failure" was to blame for yesterday’s outage which left millions of users around the world unable to access web, email or BlackBerry Messenger services.

The full statement is as follows:

"RIM update: 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 apologise for any inconvenience and we will continue to keep you informed."

The company says services have now been restored but the disruption caused a large backup of information. RIM is working to clear that at the moment so services may remain slow for a while, the company noted.

However this morning many users on Twitter are still reporting issues with web browsing and BBM.

Lord Alan Sugar of Amstrad and Apprentice fame tweeted: "In all my years in IT biz, I have never seen such an outage as experienced by Blackberry. I can’t understand why it’s taking so long to fix."

"Right, well it would appear as though Blackberry has crashed once again," said another.

Before this statement was issued the only information given out by the Canadian firm were a few short statements confirming the disruption, a promise that the company was working on it and an apology to its affected users.

Full details about what exactly happened, such as why its failover systems failed and what RIM plans to do to ensure these issues will not be repeated, have yet to be revealed.

The cause of Monday’s service disruption also remains unexplained by RIM. It is also unclear if the two incidents are even related.

UPDATE: The issue has today spread to the US. Following reports on Twitter and various blogs that services across North American were disrupted a brief RIM statement confirmed: "BlackBerry subscribers in the Americas may be experiencing intermittent service delays this morning."

The company once again apologised and said it is working to fix the issue, although as with the EMEA and South America outages, details remain scarce beyond RIM’s explanation of a "core switch failure" followed by a system that was designed to failover to a back-up switch not working as expected.