BlackBerry service to Research in Motion customers in North America was disrupted Wednesday, adding to problems in the troubled developer's European, Middle East and African markets.

Intermittent service delays may hit users in the U.S. and Canada, the Waterloo, Ontario-based carrier said. Since Monday, BlackBerry customers have been facing service woes due to problems with a server upgrade. Sprint-Nextel acknowledged its BlackBerry problems but AT&T, Verizon Communications and T-Mobile had no comment.

It is our top priority to return service to our customers, said David Yach, chief technical officer for software, during a mid-afternoon press briefing. He said the company will try to handle e-mail backlogs and said there was no evidence of hacking.

RIM's service issues come as the company faces increasing competition from other smartphone makers like Apple and Samsung Electronics as well as potential takeover or divestiture efforts brought by activist investors including Toronto's Jaguar Financial, which this week claimed support from 12 percent of shareholders.

While the majority of North American users are in the corporate or enterprise market, worldwide BlackBerry users are heavily centered among consumers. During recent riots in London, British police sought to take down RIM servers so as to prevent young people from calling and texting one another.

RIM shares Thursday dipped another 1.6 percent to $24.02 in afternoon trading, bringing their total loss this year to nearly 60 percent. That loss, as well as the failure of the BlackBerry PlayBook tablet to sell more than 200,000 units in their first quarter of introduction, spawned Jaguar's bid to shake up management.

Analysts including Jeffery Fidacaro of Susquehanna Financial speculated the service woes could be related to an upgrade to the QNX OS for the PlayBook scheduled for next quarter. RIM acquired closely held QNX because the OS was dubbed most suitable for the tablet sector,

Jaguar Financial Chairman Victor Alboini, a dedicated BlackBerry user, told IBTimes one of the crown jewels in RIM was its enormous appeal to users in developing countries, especially India, Indonesia, China and Brazil, as well as its enterprise play with North American business.

The company's own servers handle traffic mainly from headquarters in Waterloo and from a center in Slough, England, where a switch failed and service didn't automatically hand off to a back-up server.

RIM is scheduled to hold a developers conference next week in San Francisco.

The BlackBerry problems come as Apple began global downloads of its iOS 5 for all products including the iPhone 4 and new iPhone 4S. In the second quarter, Apple held an 18.4 percent share of the market, estimates IHSiSuppli, compared with RIM's 12 percent.