DETROIT—Senior officials at the U.S. Department of Transportation have at least temporarily blocked the release of findings by auto-safety regulators that could favor Toyota Motor Corp. in some crashes related to unintended acceleration, according to a recently retired agency official.

George Person, who retired July 3 after 27 years at the National Highway Traffic Safety Administration, said in an interview that the decision to not go public with the data for now was made over the objections of some officials at NHTSA.

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