The Motor Insurers' Bureau, which administers the £170 million Uninsured Drivers' Scheme, has come under fire for imposing new conditions on claimants.
Steve Donovan, a senior member of the Motoring Uninsured Loss Recoveries Association, said the changed rules will allow the MIB to strike out otherwise valid claims for compensation on technical grounds alone.
The Bureau, which handles around 40,000 claims each year, has published a revised agreement covering the estimated 1.5 million uninsured motorists on Britain's roads.
The £170m annual cost of the MIB is funded by a levy on all motor insurers.
The main change is that "the MIB shall incur no liability unless a claimant has acted as reasonably as practicable in demanding the details of an uninsured driver". The excess has been raised from £175 to £300.
Donovan said: "These restrictions only benefit motor insurers who fund the MIB."
The changes affect claims occurring after October 31, 1999.
Antony Hodari, managing partner of leading Manchester road traffic solicitors Antony Hodari & Co, is also critical of the changes. He said: "The conditions are so restrictive as to be almost impossible to comply with."
Roger Snook, MIB claims manager, said: "The agreement merely spells out what went on under the 1998 agreement." However, some time limits are looser than before. Insured parties now have 14 days instead of seven to give notice of civil proceedings.