WASHINGTON (AP) — The Obama administration is preparing to warn car owners whose air bags have been replaced in the past three years that dangerous counterfeit bags may have been installed, according to auto industry officials who have been briefed by the government.

National Highway Traffic Safety Administration alerted the industry in a series of telephone briefings Tuesday that tens of thousands of car owners may be driving vehicles with counterfeit air bags, the industry officials said. NHTSA testing has shown some of the counterfeit bags don't inflate or fail to inflate properly, they said. In at least one case, a counterfeit bag fired shards of plastic and other projectiles on impact, they said.

The officials requested that their names not be used because NHTSA had asked them not to speak publicly about the problem until after an announcement scheduled for Wednesday.

Car owners will be able to check a government website, www.Safercar.gov , or call their manufacturer or local dealership to learn whether their vehicle model is among those for which counterfeit air bags have been made, officials said.

The agency has compiled a draft list of dozens of vehicle makes and models for which counterfeit air bags may be available. NHTSA cautions at the top of the draft that the agency "expects this list to evolve over time."

If the car is on the list and has had its air bags replaced during the past three years by a repair shop other than an auto dealership, owners will be asked to bring the vehicle into a dealership to determine whether the replaced air bags are counterfeit. Some cars have as many as eight air bags.