Research In Motion, makers of BlackBerry mobile phones, have issued a statement apologising for two days of continuing service outages across Europe, Africa, the Middle East, India and South America.
BlackBerry users have experienced widespread problems with its core email, messaging and browsing services, and have taken to social media in huge numbers to express their frustration.
Many users were still reporting problems on Wednesday, despite the intermittent resumption of some services.
Until its statement on Tuesday RIM had refused to make any substantial comment on the problem.
The company has now admitted that the breakdown was caused by a central technical failure.
In its statement, the company said:
"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."