DETROIT, Michigan - US safety regulators have closed a government safety probe into GM's Chevrolet Volt, saying it doesn't believe Volts (or any other electric vehicle) pose a greater fire risk than petrol-powered vehicles.The National Highway Traffic Safety Administration (NHTSA) noted GM's voluntary fix to help prevent damage to the battery pack in a severe side impact and closed the investigation without requiring a formal recall from GM, the Detroit News reported. In response, GM said the NHTSA's decision to close its investigation was "consistent with the results of our internal testing and assessment".QUICK FIXEarlier in January, 2011, GM unveiled a plan to repair the Volts by adding a new steel structure to the battery pack to protect it from intrusion in a severe side crash. The automaker also added new sensors.GM dealers were allowed to continue selling the unrepaired cars since the company insisted these remained safe to drive, the Det News added. GM said it plans to begin building Volts again in the first week of February. It also expects to get parts to dealers to start repairing Volts "in a couple of weeks".However, the NHTSA has issued new safety guidelines for emergency crews dealing with a crashed electric vehicle.GENERAL RISK"Generally all vehicles have some risk of fire in the event of a serious crash," the NHTSA said. "However, electric vehicles have specific attributes that should be made clear to consumers, emergency response reams, tow-truck operators and storage facilities."It warned owners of electric vehicles "do not store a severely damaged vehicle with a lithium-ion battery inside a structure or within 15m of any structure or vehicle".The NHTSA said there were no actual complaints of fires but added "the closing of the investigation does not constitute a finding by the NHTSA that a safety-related defect does not exist. The agency reserves the right to take additional action if warranted by new circumstances".