May 7 (Reuters) - U.S. auto safety investigators are

seeking detailed answers and documents from Tesla in an

investigation into the automaker's December recall of more than

2 million vehicles to install new Autopilot safeguards.

The National Highway Traffic Safety Administration (NHTSA)

said last month it was opening the probe after receiving reports

of 20 crashes involving vehicles that had the new Autopilot

software updates installed under Tesla's recall.

The NHTSA sent Tesla an information request letter made

public Tuesday seeking details of the recall and documents by

July 1.