LONDON (AP) — Email and messaging glitches that have plagued BlackBerry users around the world for a second day were caused by a core switch failure, the smartphone's maker said Tuesday.

Research in Motion Ltd. said the disruptions — which affected users from Europe to Latin America — were due to a failure within the company's own infrastructure. A transition to a back-up switch did not function as tested, causing a large backlog of data, RIM said.

It was the first time the company offered an explanation of the outage since problems first occurred Monday morning.

"We are now working to clear that backlog and restore normal service as quickly as possible," the company said in a brief statement.

The disruptions affected Blackberry users in Europe, the Middle East and Africa, India, Brazil, Chile, and Argentina.

RIM said early Tuesday that the problems were resolved and that services were operating normally, but hours later it acknowledged that the disruptions were continuing.

RIM apologized for "any inconvenience," as Twitter and the Internet lit up with condemnation over a delayed response to problems some users had reported for hours.

In Britain, Vodafone UK told customers via Twitter that service was not fully restored. Rival T-Mobile UK blamed "a European-wide outage on the BlackBerry network" which it said was affecting all mobile operators. There also were reports of problems elsewhere in Europe, such as Spain.

Etisalat, which operates in the United Arab Emirates, apologized for "the further interruption" to Blackberry services, "once again due to RIM problems."

Kenya's Safaricom Ltd. said on Twitter that its Blackberry customers were experiencing a "technical fault," while South Africa's Vodacom told subscribers the issues were affecting multiple networks and countries.

There were no reports of any problems in the U.S.

Angry smartphone users took to Twitter to vent frustration with the company and bemoaned the loss of their messaging capabilities, questioning why the company took so long to restore services.