Consumer Reports magazine backed off Thursday from its recent negative report on infant car seats, saying test crashes were conducted at speeds higher than it had claimed.

The magazine reported Jan. 4 that most of the seats it tested "failed disastrously" in crashes at speeds as low as 35 mph. In one test, it said, a dummy child was hurled 30 feet.

Consumer Reports said Thursday it had received information from the National Highway Traffic Safety Administration showing that the speeds at which its side-impact tests were conducted were higher than the 38.5 mph reported.

In fact, the NHTSA said the crash tests were conducted under conditions that would represent being struck at more than 70 mph — twice as fast as the magazine claimed, said NHTSA administrator Nicole Nason.

"Consumer Reports was right to withdraw its infant car seat test report and I appreciate that they have taken this corrective action," Nason said. "I was troubled by the report because it frightened parents and could have discouraged them from using car seats."

The Yonkers-based magazine said it would review its study, retest the car seats and publish a new article as soon as possible.

The magazine tested the type of infant car seat that faces the rear and snaps in and out of a base. It found only two of the 12 seats worth recommending, and it urged a federal recall of one seat, the Evenflo Discovery. Evenflo had immediately disputed the tests' validity.

On Thursday, Consumer Reports spokesman Ken Weine said a recall was still being urged for the Discovery and for another seat which was judged unacceptable because it did not fit well in several cars. Evenflo spokeswoman Jam Stewart said the company would comment later.

The original report found that all the car seats except the Discovery performed adequately in 30 mph frontal crashes, which is the standard for seats sold in the United States. But it noted that cars are tested by the NHTSA at higher speeds — 35 mph for frontal crashes and 38 mph for side crashes — so the magazine said it tested the seats at those speeds.

In the 35-mph frontal test, Consumer Reports had said the seats separated from their bases, rotated too far or would have inflicted grave injuries, Consumer Reports said. At 38 mph, four seats flew out of their bases following side impact.

"When NHTSA tested the same child seats in conditions representing the 38.5 mph conditions claimed by Consumer Reports, the seats stayed in their bases as they should, instead of failing dramatically," Nason said.

Weine said Thursday there was no information casting doubt on the 35 mph crashes.

He said an internal investigation was under way and he could not yet say how the test may have gone wrong, or who, if anyone, was to blame.

"This is very early," he said. "We found this information out very recently and as soon as we did we wanted to take the most important step which is openly communicating with consumers."

The magazine asked its readers and others who may have learned of the tests "to remember that use of any child seat is safer than no child seat, but to suspend judgment on the merits of individual products until the new testing has been completed and the report republished."