Consumer Reports said it cannot recommend Apple's iPhone 4 to buyers after tests confirmed the device's well-publicized reception glitches, and the magazine said it will not do so until Apple finds a permanent and free fix.
The magazine, which tests electronics, appliances and other items, added that AT&T Inc., the iPhone's exclusive U.S. carrier, was not necessarily the culprit.
The influential nonprofit organization, which publishes guides on everything from cars to TVs, said in a report released Monday that it also tested other phones - including the iPhone 3GS and Palm Pre - and found none had the signal-loss problems of Apple's latest iPhone.
"Our findings call into question the recent claim by Apple that the iPhone 4's signal-strength issues were largely an optical illusion caused by faulty software," Mike Gikas of Consumer Reports wrote in a blog post Monday.
Apple did not respond to messages seeking comment.
The iPhone 4 topped Consumer Reports' updated ratings list for smart phones for its sharp display and "best video camera we've seen on any phone," according to the blog.
The report was the latest blow to the iPhone 4, which went on sale June 24. Though 1.7 million units were sold in its first three days on the market, the device has been plagued by complaints of poor reception. Many of the complaints involve a wraparound antenna whose signal strength is said to be affected if touched in a certain way.
Apple shares closed down nearly 1 percent at $257.29 Monday. It has been sued by iPhone customers in at least three complaints related to antenna problems.
"When your finger or hand touches a spot on the phone's lower left side . . . the signal can significantly degrade enough to cause you to lose your connection altogether if you're in an area with a weak signal," Gikas wrote. He recommended covering the gap in the wraparound antenna with duct tape or other nonconductive material.
Meanwhile, a monopoly abuse lawsuit against Apple and AT&T over the iPhone can continue as a class action, a judge in California has ruled. An amended complaint filed in June 2008 deals with Apple's practice of "locking" iPhones with AT&T's network and with Apple's control over the applications that can be installed.