Insurers risk losing money on their motor books if they do not set their premiums to reflect the high cost of aluminium used in some new cars, WNS Assistance has warned.

The motor claims specialist said that aluminium in new models is increasing repair costs by at least 25%.

Aluminium-bodied vehicles could also be off the road longer than steel-bodied vehicles due to unique difficulties involved in the repair, said the company.

Tim Rankin, of WNS, said that these extra costs would be borne by insurers unless they factored them into their premium calculations.

New models that use aluminium in their construction include the Audi A2, A6 and A8, the BMW 5 and 6 series and the Renault Espace.