Progress in cutting road casualty rates has varied dramatically across the UK, according to an analysis of accident figures.

The reduction in the number of people killed or seriously injured (KSIs) is much higher in London than the national average and much lower in Wales.

On the basis of KSIs, roads in Scotland and Northern Ireland are far safer than those in England. The reduction rates were 33 per cent north of the Border and 35 per cent in Northern Ireland.

The analysis came in a report published by the RAC Foundation and the Parliamentary Advisory Committee for Transport Safety.

The report showed the reduction between 2010 and 2013 in the number of KSIs compared with the average KSI figure for the period 2005 to 2009.

The report said the figures hid a recent flattening out of the overall downward trend with the most dramatic casualty reduction in this period being seen in 2010.

While car occupant safety has improved markedly, the situation among vulnerable road users (pedestrians, cyclists, motorcyclists) has been less good, the report said.

Although deaths in this group have declined they are now a larger proportion of all road deaths, rising from 46 per cent in 2005-09 to 49 per cent in 2013. The absolute number of cyclists seriously injured has risen.

RAC Foundation director Professor Stephen Glaister said: "The UK risks breaking apart in terms of road safety policy with different administrations having varying levels of power, funding and political will to deal with death and injury on the highways.