A fire involving a General Motors Co Chevy Volt has prompted a U.S. government safety investigation of batteries used to power electric vehicles.

The National Highway Traffic Safety Administration said in a statement on Friday that it has also asked other manufacturers who make electric cars or who plan to do so for information on how they handle lithium-ion batteries. This request also includes recommendations for minimizing fire risk.

NHTSA said it does not believe the Volt or other electric vehicles are at greater risk for fire than gasoline-powered engines.

The Volt crash occurred last May at a test facility in Wisconsin but the fire did not break out until more than three weeks later.

A NHTSA official told Reuters that the crash damaged the battery pack but the exact reason for the latent fire is not yet clear.

Engineers and auto safety advocates have raised precautions regarding battery overheating and possible fires similar to those that have occurred in laptop computers.

GM conducted follow-up crash tests with no fire, NHTSA said. The agency plans additional testing in coming weeks with the help of Energy Department experts.

Nissan Motor Co Ltd makes the other mass produced electric car, the Leaf.

GM said in a statement that the Volt is safe and poses no undue risk to consumers.

(Reporting by John Crawley; Additional reporting by Ben Klayman; Editing by Derek Caney and Gerald E. McCormick)