US officials said Friday they had launched an investigation into electric vehicle safety after a damaged lithium battery in a Chevy Volt caught fire three weeks after a crash test.

Safety officials said there is "no evidence" that electric cars are at a greater risk of fire than gasoline-powered ones, although there have been fire problems with lithium batteries used in computers.

Nobody was hurt in the fire which damaged property at a government testing facility in Wisconsin in May.

It is the only case of battery-related fire recorded after "numerous" crash tests, the National Highway Transportation Safety Agency said.

The agency said it will be conducting further tests on the batteries and is working with automakers to make sure they have "appropriate post-crash protocols."

It is also working to inform consumers and emergency responders of the necessary safety precautions.

"It is common sense that the different designs of electric vehicles will require different safety standards and precautions," the agency said in a statement, adding that electric vehicles "show great promise as an innovative and fuel-efficient option for American drivers."

General Motors, owner of the Chevrolet brand, said it has not received any reports of trouble from dealers, customers or the OnStar systems installed in the 5,000 Volts which have been sold since the vehicle's launch last year.

"So far we've had absolutely zero reports of trouble," GM spokesman Greg Martin told AFP, adding that the Volt has a five-star safety rating.

GM said it has already developed protocols to depower the battery of an electric vehicle after a significant crash and would be working with federal regulators to further investigate the fire.

"First and foremost, I want to make this very clear: the Volt is a safe car," Jim Federico, GM's chief engineer for electric vehicles, said in a statement.

Federico acknowledged that safety protocols for electric vehicles "are clearly an industry concern."

"We are working with other vehicle manufacturers, first responders, tow truck operators, and salvage associations with the goal of implementing industry-wide protocols," he said.