NEW YORK (AP) — BlackBerry service was being restored Wednesday morning after an overnight outage that left millions of users without mobile access to their e-mail on the popular device.

Research in Motion Ltd., the Canadian company that provides the devices and e-mail service, said the service interruption began Tuesday night, affecting users in North America.

WALL ST. JOURNAL: Problems hit users worldwide

COMPUTERWORLD REPORT: Outage started on West Coast

“A service interruption occurred Tuesday night that affected BlackBerry in North America,” according to a statement from RIM. “E-mail delivery was delayed or intermittent during the service interruption. Phone service on BlackBerry handsets was unaffected.”

CNET reported that, according to an automated message on RIM’s customer service hotline, the company is “experiencing technical difficulties with our BlackBerry service that may cause delays in sending or receiving messages.”

This is likely due to a backlog of e-mails stemming from the service outage, which was first reported on the New York metro news site WNBC.com. The outage is believed to have originated around 5 p.m. PT on Tuesday. WNBC then reported that service was resumed around 4 a.m. Wednesday but that problems with a backlog of data were likely.

“Root cause is currently under review,” RIM said in its statement, “but service for most customers was restored overnight, and RIM is closely monitoring systems in order to maintain normal service levels.”

It wasn’t immediately clear whether the problems affected all cellular carriers that offer BlackBerry service.

On the BlackBerryForums.com discussion site, some members also indicated that they could not access Internet-browsing features in addition to e-mail.

RIM initially acknowledged the problem through a recorded message that is played when calls are placed to the BlackBerry customer service hotline, stating that the company is “currently experiencing a service interruption that is causing delays in sending or receiving messages.”

No further updates have been provided, and no time frame has been given for dealing with the problem, but the automated message assured concerned callers that they would be kept in the loop.

Last week, RIM reported that it added about 1 million BlackBerry subscriber accounts during the first three months of 2007, bringing its total subscriber base to 8 million.

Jitters about the outage sent RIM’s share price sliding in the opening minutes of Wednesday’s trading, but the stock recovered quickly. The stock was changing hands at $130.65 a share, down 62 cents, on the Nasdaq Stock Market after falling as low as $128.80.