Key US lawmakers on Thursday demanded General Motors detail its handling of potential safety problems with the Chevrolet Volt after three of the Volt's electric batteries caught fire following safety tests.

Republican Representative Darrell Issa, who chairs the House Committee on Oversight and Government Reform, and two colleagues pressed GM CEO Daniel Akerson in a letter to address their concerns by December 21.

"In light of recent reports about the lithium-ion battery system of the Chevrolet Volt, we write with serious questions about the safety of the Volt and the advanced technology developed by General Motors (GM)," they said.

The lawmakers called it "alarming" that GM officials knew of the problems in June but made no comment on the incidents until media reports detailed them in November.

"GM continued to market and sell Chevrolet Volts to American consumers, fully aware of potentially serious safety deficiencies affecting the vehicle's battery system. GM took no steps to notify consumers or the public in general of this problem," they wrote.

The lawmakers pressed GM to say when it first learned of potential safety issues with the Volt's batteries, whether and when it notified regulators about the problem, and how it addressed the issue with Volt owners.

And they asked whether any aide to President Barack Obama, whose administration has touted the Volt as an example of promising technology that will help battle global warming, pressured the firm to delay disclosing the issues.

Republicans have assailed Obama's "clean energy" agenda since he took office, notably seeking evidence that his administration steered funds meant as economic stimulus to companies with political ties to the president.

Those efforts have yet to turn up a smoking gun, and the White House flatly denies any wrongdoing.

GM in late November insisted the Volt was safe to drive after the National Highway Traffic Safety Administration announced an investigation into the issue.

The investigation was launched after a damaged lithium battery in a Volt caught fire three weeks after a crash test.

The NHTSA sought to recreate the fire last week by intentionally damaging the battery compartment and breaking its coolant line. In two of the tests, the batteries caught fire, it said.