Millions of BlackBerry users remained without service on Wednesday as a three-day outage spread to North America.

“BlackBerry subscribers in the Americas may be experiencing intermittent service delays this morning,” Research in Motion, maker of BlackBerry smartphones, said in a statement. “We are working to resolve the situation as quickly as possible and we apologize to our customers for any inconvenience. We will provide a further update as soon as more information is available.”

The service outage started on Monday with customers in the Middle East, Europe and Africa, before spreading to South America on Tuesday. On Wednesday morning it appeared to hit the United States and Canada. The outage appears primarily to affect text messaging and Internet access from the mobile phones, not necessarily their ability to place calls.

“BlackBerry users in Canada have been cut off from their smartphone’s messaging, e-mail and Internet services,” the Canadian news site CP24 wrote. Those sentiments were echoed by the CBC, the Canadian broadcaster, which put out a breaking news tweet saying e-mail and texting services had been interrupted in some parts of Canada.

NPR reported some of its staffers in North America had experienced outages. CNN employees in the United States also were having trouble accessing some data connections and text messages. Twitter users complained of similar issues.

In a statement released Tuesday, 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.”

The company said it was working to fix the problem.

“A large backlog of data was generated and we are now working to clear that backlog and restore normal service as quickly as possible,” the Tuesday statement said. “We apologize for any inconvenience and we will continue to keep you informed.”

There are about 70 million BlackBerry users worldwide. RIM has not commented on how many users are affected, but reports suggest the number of users without some sort of service has climbed into the millions.

BlackBerry users, many of whom use the devices primarily for business purposes, were less than pleased with the outage.

“#DearBlackberry I can’t work, I can’t study, please, please come back from that coma! Don´t go into the light!! It´s a baaad light!!” a Twitter user named @marianaae wrote.

“What did the one #Blackberry user say to the other?……….nothing….,” said another Twitter user, @giselewaymes.

“And iPhone users everywhere smile smugly and search for the ‘I Told You So’ app,” wrote another.

This is not the first time RIM has faced a major service outage.

“I have been an analyst for 25 years and have watched RIM wrestle with this same outage problem time after time. Every few years we get pinched by yet another major problem,” tech analyst Jeff Kagan said in a statement.

This outage, however, comes at a particularly bad time for RIM, since it faces increasing competition in the smarpthone market, Kagan says. Apple’s iPhone and phones on the Google Android operating system have been gaining ground, and the new iPhone 4S goes on sale Friday.

The tech blog Electronista wrote:

“RIM’s outage is now one of its largest in recent memory and is now edging even closer to the iPhone 4S launch than before, leading to a possible temptation for those already looking to upgrade their phones. Commentary on Twitter has shifted gradually from frustrated patience to open anger and has led some to remark that they’re now likely to switch to the iPhone, Android, or another platform.”