WASHINGTON, July 10 (Reuters) - A U.S. auto safety

regulator said on Wednesday that three people have been killed

and two seriously injured in the last nine months by low-cost

faulty replacement air bag inflators.

The National Highway Traffic Safety Administration urged

used car buyers and owners to beware of substandard imported

inflators that can cause death or serious injury in a crash. The

agency said the inflators, which had been installed after prior

crashes, malfunctioned in subsequent collisions, sending large

metal fragments into drivers.

"These suspect replacement parts are often manufactured by

foreign companies with little to no reputation of quality

manufacturing or experience, sold at prices far below the cost

of quality genuine equipment, ordered online ... and installed

by those other than reputable repair shops or manufacturer

dealerships," the agency said.

The NHTSA added that consumers should obtain a

vehicle-history report before purchasing a used vehicle and, if

it was in a prior crash, visit an independent mechanic for an

air bag inspection to ensure the parts are genuine.

"If it's too good to be true, it likely is - and it could be

deadly," the agency said.

For years, NHTSA has investigated air bag inflators that can

degrade after long-term exposure to high humidity.

More than 30 deaths worldwide, including 26 U.S. deaths, and

hundreds of injuries in various automakers' vehicles since 2009

have been caused by Takata air bag inflators that can explode,

unleashing metal shrapnel inside cars and trucks.

Over the last decade, more than 67 million Takata air bag

inflators have been recalled in the United States by more than

20 automakers, and more than 100 million inflators recalled

worldwide, in the biggest auto safety callback in history.