OTTAWA (Reuters) - Research in Motion shares fell about 4 percent on Friday after a Fortune.com story said that a high-speed wireless version of its BlackBerry smartphone for top U.S. phone company AT&T Inc is facing delays.

The introduction has been pushed back as far as August from June, the story on Fortune magazine’s website said, citing unnamed people close to the companies. The reason for the delay was unclear, but AT&T had worries about call quality, the report said.

“RIM’s policy is to decline comment on rumors and speculation,” spokeswoman Marisa Conway said via email. AT&T declined comment on the timing of any future product plans.

A delay for the phone, which the report said may be called Meteor, could have an impact on phone shipments and subscriber growth.

Shares in Waterloo, Ontario-based RIM dropped 4.1 percent at mid-session on Friday to C$120.50 on the Toronto Stock Exchange and to $118.59 on Nasdaq.

AT&T’s Chief Financial Officer Rick Lindner referred to plans for a high-speed BlackBerry with third generation, or 3G, technology on a quarterly earnings conference call earlier this week, but did not give a date for the launch.

“We’re just starting to see a BlackBerry 3G come out. As those integrated devices move to 3G, I think that will be the next catalyst to drive stronger 3G growth,” he said.

“New customers coming in today, if they are buying a phone, many times, particularly postpaid customers, they’re primarily going to 3G.”

RIM has said it will introduce devices based on HSDPA, a high-speed 3G wireless technology that is popular in Europe and used by AT&T.

“Certainly going to HSDPA is something that’s very important to us in the near term,” Chief Executive Jim Balsillie told Reuters in a February interview.

TD Newcrest analyst Chris Umiastowski speculated about the timing of RIM 3G device shipments in a recent note that lowered his earnings estimates and stock target.

“We believe the device is on track to be available either at the end of May or in June. That said, we are not yet clear on when AT&T will start selling the device,” he wrote.

“Perhaps it will launch in Europe (with Vodafone) prior to hitting North American soil?…A launch of this upcoming 3G device either by AT&T or Vodafone should result in a significant number of hardware shipments within the first full quarter of launch.”

AT&T and rival carrier Verizon make up about 40 percent of RIM’s new subscriber growth, the analyst estimated.

AT&T, the exclusive U.S. carrier for Apple Inc’s iPhone, a competitor to BlackBerry, hinted at a U.S trade show earlier this month that it expects to have a 3G version of iPhone in coming months. It did not give a specific date.