More civilians are killed or seriously injured in accidents involving Thames Valley Police cars than almost any other force, official figures have revealed.

According to the Home Office, six people have died as a result of smashes over the last five years - an average of more than one death every 12 months.

Only two forces in England and Wales have worse safety records - the Met and Greater Manchester.

The worst period for civilian fatalities in the Thames Valley was 2002/2003, when there were three deaths.

In the same year, 13 people were seriously injured - two of them police officers - with Thames Valley force vehicles involved in a total of 992 crashes.

That is equivalent to almost three accidents every day. Again, only the Met and Greater Manchester recorded more smashes.

Home Office figures show the situation in Thames Valley has been getting worse. In 1998/99, there were 888 accidents and one serious injury.

By 2002/03 - the latest figures available - this had risen 11 per cent to 992 accidents and 13 severe injuries.

Not included in these figures is the death of Oxford Brookes University student Emily Higson.

Pc Stephen Norman, 44, based in Oxford, is charged with causing the death of the 22 year-old, who was knocked down in Cowley Road, near the junction with Divinity Road, late on November 16 last year.

The Government has accepted too many police cars were crashing and said forces across the country had agreed they had to cut accident rates.

Home Office minister Caroline Flint said: "The Government welcomes the recognition by the Association of Chief Police Officers that they must work to reduce the number of collisions involving police vehicles."

Forces nationwide were told last month to beef up their car chase procedures by the Police Complaints Authority, which outlined tougher guidelines to improve officers' driving.

Sir Alistair Graham, PCA chairman, made clear the situation was unacceptable, saying he was "vigorously seeking ways of improving police performance and reducing the numbers of deaths".

Among the recommendations put forward were calls for police drivers and traffic controllers to get thorough and regular testing of their skills. Sir Alistair also said senior officers would be held to account for any fatal smashes.

Malcolm Collis, manager of Thames Valley Police's roads policing department, said: "Thames Valley is the largest non-metropolitan force in the country and therefore commits proportionally more resources to a high number of incidents each year.

"The Force records a wide-range of incidents as collisions involving police vehicles.

"In the vast majority of cases, these incidents involved fleeing offenders causing injury to themselves and others. Very few involve actual contact with a police vehicle.

"We are dedicated to operating in a safe and responsible manner and have comprehensive controls on all police drivers. As well as intensive training we operate an internal penalty points policy, continuous assessment and retraining.

"The force regularly reviews and updates its attendance and pursuit policy to ensure that resources respond appropriately.

"Any officer suspected of dangerous or irresponsible driving is vigorously investigated, and where appropriate will be prosecuted."