Consumer Reports, the influential magazine for product reviews, gave the thumb's down Monday to Apple's new iPhone because of reception problems it said were caused by a design flaw.
"Consumer Reports' engineers have just completed testing the iPhone 4, and have confirmed that there is a problem with its reception," the magazine said on its website, ConsumerReports.org.
"When your finger or hand touches a spot on the phone's lower left side - an easy thing, especially for lefties - the signal can significantly degrade enough to cause you to lose your connection altogether if you're in an area with a weak signal," it said.
"Due to this problem, we can't recommend the iPhone 4."
Apple earlier this month said that it had used erroneous formulas to calculate signal strength for the iPhone 4 and promised to issue a free software patch to resolve the issue that has already triggered lawsuits.
The California gadget maker denied that reception problems were due to faults in its new antenna system, which is incorporated in the casing.
Consumer Reports rejected Apple's explanation.
"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," it said.
Consumer Reports said it had tested three iPhone 4s and other devices, including a previous iPhone model, in the same conditions, but "none of those (other) phones had the signal-loss problems of the iPhone 4."
Consumer Reports said it had found "an affordable solution for suffering iPhone 4 users: Cover the antenna gap with a piece of duct tape or another thick, non-conductive material."
The magazine said the iPhone performed well in other ares.
"It sports the sharpest display and best video camera we've seen on any phone," it said, and "outshines its high-scoring predecessors with improved battery life and such new features as a front-facing camera for video chats."