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March 19 (Reuters) - The U.S. National Highway Traffic Safety Administration has intensified its probe into millions of Tesla vehicles, upgrading it to a more detailed engineering analysis of the company's driver assistance system, the auto safety regulator said on Thursday.

The probe covers roughly 3.2 million vehicles, across multiple models the company has sold.

The move marks a significant escalation that could lead to a recall or other enforcement action if regulators find a safety defect.

Tesla did not immediately respond to a Reuters request for comment.