NEW YORK, Oct 12: A three-day disruption to BlackBerry services spread to North America on Wednesday, frustrating millions of users of the Research In Motion (RIM) devices just two days before rival Apple’s new iPhone 4S goes on sale.

RIM advised clients of an outage in the Americas and said it was working to restore services as customers in Europe, the Middle East, Africa and India continued to suffer patchy email and no access to browsing and messaging.

RBC analysts Mike Abramsky and Paul Treiber estimated that about half of BlackBerry’s 70 million subscribers outside North America could be affected.

RIM, which had said on Tuesday services had returned to normal, said later it was still working to resolve the problem.

“The messaging and browsing delays ... were caused by a core switch failure within RIM’s infrastructure,” it said. “As a result, a large backlog of data was generated and we are now working to clear that backlog and restore normal service.”

RIM did not say how long it might take. In India, top mobile carrier Bharti Airtel sent text messages to customers saying BlackBerry services were likely to be restored in four to five hours.

The service disruptions are the worst since an outage swept north America two years ago, and come as Apple prepares to put on sale its already sold-out iPhone 4S on Friday.

Many companies, no longer seeing the need to pay to be locked into RIM’s secure proprietary email service, have already began allowing employees to use alternative smartphones, particularly Apple’s iPhone, for corporate mail.

RIM has made inroads into the youth market and into developing economies attracted by its free BlackBerry Messenger (BBM) service, partially compensating for its losses in the corporate market in North America and Western Europe.

RBC said the latest crisis could hurt RIM’s reputation in these key markets, particularly after high-profile tussles with states whose governments demanded access to encrypted communications for security reasons.

“Following recent high-profile sovereign challenges to open up RIM’s secure networks... these outages create another highly visible PR challenge, coming in markets where the company is still growing,” its analysts wrote in a note.