Insurers were forced to pay over £121m to the NHS last year to cover the treatment costs of road traffic accident victims, figures released to parliament have revealed.
The figures show the amount clawed back from the insurance industry by hospitals has more than quadrupled since 1999 when the law was introduced.
In 1999, £30m was claimed back by hospitals. This increased to £121,500,570 in 2005/06.
In 1999 the law was changed to allow NHS trusts to reclaim treatment costs from motor insurers in cases where fault had been established and compensation paid.
Before 1999 hospitals could only recoup £21 from a road accident victim towards the cost of their treatment.
The 1999 Act set fixed rates of more than £400 per day for patients who were not admitted, and more than £500 for those forced to stay in hospital. In 2004, the rates were changed allowing hospitals to recover up to £34,800 per case.
Conservative MP David Amess said drivers are being forced to pay at least £5 extra per year as part of the government's regime. He criticised the government for changing the rates in March 2004 as some major hospitals were claiming more than £500,000 a year from insurance companies.
An ABI spokesman described the NHS clawbacks as "another pressure" on insurers, although it was not the only reason for rate increases.
Richard Ellis, head of motor claims at Norwich Union, said the clawbacks did "end in rate increases".