The National Highway Traffic Safety Administration (NGTSA) is demanding that ARC Automotive recall 67 million inflators in the US because they could explode and hurl shrapnel.

At least two people have been killed in the US and Canada, and seven others have been hurt as a result of defective ARC inflators, the agency said.

In a letter posted Friday, the agency told ARC that it has tentatively concluded after an eight-year investigation that the company's front driver and passenger inflators have a safety defect.

"Air bag inflators that project metal fragments into vehicle occupants, rather than properly inflating the attached air bag, create an unreasonable risk of death and injury," Stephen Ridella, director of NHTSA's Office of Defects Investigation, wrote in a letter to ARC.

But ARC responded that no defect exists in the inflators, and that any problems are related to isolated manufacturing issues.

The next step in the process is for NHTSA to schedule a public hearing. It could then take the company to court to force a recall.

General Motors is recalling nearly 1 million vehicles equipped with ARC inflators.

The company said that it's doing the recall, which expands previous actions, "out of an abundance of caution and with the safety of our customers as our highest priority."

In its response to the recall demand, ARC Vice President of Product Integrity Steve Gold wrote that NHTSA's position is not based on any objective technical or engineering conclusion about a defect, and its recall exceeds the agency's legal authority.

Australian Associated Press