A paper in the British Medical Journal compared police statistics, used by the Government for its figures, with hospital statistics from 1996 to 2004.
Police figures showed that by 2004 the number killed or seriously injured (KSI) on the roads had dropped by almost a third, with a 32% drop in serious but non-fatal injuries.
But the researchers from Oxford University and the South East Regional Public Health Group found hospital figures for non-fatal road injuries showed that rates hardly changed over the same period.
The authors think the discrepancies were down to an increase in under-reporting of injuries by the police.
They recommend more investigation is needed on the Government’s progress towards reducing the number of deaths and serious injuries by 40% by 2010.
Paul Smith, founder of the Safe Speed road safety campaign, said the news was evidence of the Government’s failing road safety policy.
He said: ‘The roads are not getting safer.
‘Government road safety policy, supported only by dodgy statistics, has failed. The Government measures road safety and sets targets in KSIs.
‘The new data shows no improvement at all in KSI despite the proliferation of speed cameras and lower speed limits. Clearly these measures are not delivering the safety improvements claimed and promised.
‘Speed cameras are at the centre of the failure. The Department for Transport must immediately pull the plug on the failed and dangerous speed camera programme.’
A Department for Transport report into potential statistical inaccuracies concluded that both police and health databases had their weaknesses.
It said: ‘No perfect database exists. ‘However, the STATS19 database is cross-checked and validated to a certain extent both at local and at national level, whereas the health databases are essentially a descriptive record for health audit purpose and are not internally validated as such.’