U.S. safety officials believe driver error may be behind the crash in New York of a Toyota Motor Corp Prius that has been investigated as a possible case of unintended acceleration, federal investigators said on Thursday.

The National Highway Traffic Safety Administration (NHTSA) said that an analysis of the 2005 hybrid's black box data recorder found no braking just before it hit a stone wall in the Westchester County town of Harrison on March 9. The agency also said the throttle was wide open, prompting investigators to suspect the gas pedal may have been inadvertently applied instead of the brake.

Police said it was premature to draw conclusions in the second of two recent high-profile complaints of unintended acceleration in Toyota's best-selling Prius.

Toyota has recalled more than 8.5 million vehicles worldwide since October for unintended acceleration due to loose floor mats that can jam the accelerator and gas pedals that do not spring back as designed.

The recalls cut across Toyota's product line.

NHTSA and Toyota are again investigating whether unintended acceleration could also be tied to non-mechanical or equipment causes, specifically any problem with the software-run electronic throttles. Toyota says that component is sound and NHTSA has never found any problems in previous investigations.

A Toyota spokeswoman said the company would not comment on the Harrison case until police release the results of their investigation.

Acting Chief Anthony Marraccini said police must evaluate the data, but that a full report would be ready soon.

It is absolutely premature to make any conclusive determination regarding this investigation and it's important to keep in mind that some of the data obtained is simply an instantaneous snapshot of the event and not a streaming video, Marraccini said.

The data recorder captures speed, braking, throttle position and other parameters in the seconds just before and after a crash.

In the New York crash, a 56-year-old woman pulling out of a driveway zoomed across a busy street and into a wall, knocking out some large boulders.

The woman, a housekeeper who was not identified, sustained a knee injury, according to a report filed with the federal safety agency's consumer complaint database.

Police said floor mats were not a factor in the New York case, which followed a more widely publicized incident a day earlier.

James Sikes, 61, said his 2008 Prius accelerated unexpectedly and uncontrollably as he passed another vehicle on a San Diego-area freeway. He eventually stopped the car with the help of police.

Police said they had no reason to doubt Sikes. NHTSA said tests on the car were inconclusive and it may never know if anything unusual happened with the vehicle.

Toyota said it found no evidence to support Sikes's account, saying there was nothing to indicate he applied the brakes forcefully enough to stop the speeding vehicle. NHTSA said braking systems worked properly in follow-up tests.

(Reporting by John Crawley in Washington and Bernie Woodall in Detroit; Editing by Bernard Orr)

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