The growing trade in cheap, used airbags could cost lives, according to a new report.
The research, by accident management company Accident Exchange, suggests that the unregulated market could result in defective airbags being sold to unsuspecting motorists.
The Department for Transport recommends that drivers should not fit second-hand airbags, but there are no laws to enforce this, or limit the sale, handling and maintenance of such equipment.
According to the research, there are up to 3000 used airbags offered for auction online at any given time, often with little or no knowledge of the unit's history.
Steve Evans, chief executive of Accident Exchange, said: 'Buying a second-hand airbag may save you money, but it could cost you your life.
'Who is selling these airbags? Which cars are they going into and who is fitting them? More importantly, why were they removed from the original vehicle in the first place? The market should be regulated.'
The research also referred to a 2008 report by the American National Highway Traffic Safety Administration, which found that in 255 of the 1446 fatal crashes it reviewed, the vehicle's airbags had not been properly replaced after a previous accident.