An executive from Japan's Takata Corp told U.S. senators on Thursday that the supplier is urgently trying to ramp up replacement parts for millions of vehicles equipped with potentially deadly air bags, but said it may not be able to move quickly enough.
The U.S. auto safety regulator also warned of the risks of moving to a nationwide recall, as senators have urged, saying such a move could divert replacement parts from humid regions where the defective air bags are more likely to rupture upon deployment, shooting metal shards into cars.
At least five fatalities have been linked to the defect so far, mostly in the United States.
Read More Takata, auto executives to face Senate over deadly air bag scandal
The hearing by the U.S. Senate Commerce Committee exposed several blind spots of regulators and the auto industry about the scope and urgency of the air bags' dangers.
Around 16 million cars with Takata air bags have been recalled worldwide, with more than 10 million of those in the United States. But regulators and Takata - which supplies one in five air bags globally - have yet to pinpoint why the parts are at risk.
Hiroshi Shimizu, Takata's senior vice president for global quality assurance, acknowledged on Thursday that even if the company ramps up production of replacement kits beyond the current pace of 300,000 a month, it may still not have enough parts.