SINCE mobile speed cameras were introduced at some of Bristol's worst accident blackspots, there have been more than 4,000 crashes on the roads they watch.

Figures released by the Department for Transport, courtesy of Avon and Somerset police, show that 481 people have been seriously injured or killed on the 80 roads monitored by the cameras since 2002.

The worst affected road in Bristol is Park Row in the city centre, where mobile speed cameras were introduced in 2002. Since that year there have been 681 accidents and 84 deaths or serious injuries.

The stretch of road including Cheltenham Road, Gloucester Road and Stokes Croft is also bad, with 425 accidents since 2002 when cameras were first used there, and 53 deaths and serious injuries in that time.

Bristol has seen a total of 2,974 accidents on the roads monitored by the mobile cameras. Neighbouring authorities did not have such high numbers of accidents and fatalities.

In Bath and North East Somerset, there have been 283 accidents on roads monitored by mobile cameras; in South Gloucestershire there have been 429 accidents; and in North Somerset there have been 462 accidents.

On April 1 this year, Safety Camera Partnerships around the country were disbanded after the Government ended their funding.

As a consequence, fixed speed cameras and red light cameras in the Avon and Somerset police force area were switched off, but the force still uses mobile units to catch speeding drivers.

The accident statistics were revealed after the Department for Transport urged local authorities and police forces to make full speed camera data available online.

Road Safety Minister Mike Penning said: "Local residents have a right to expect that when their council spends money on speed cameras, they publish information to show whether those cameras are helping to reduce accidents or not.

"I hope that this information will help local people to make informed judgements about the impact cameras are having on their local roads."

Brian MacDowell, of the Association of British Drivers, said: "Mobile cameras operated by the police seem to have come more to the fore," he said. "But if you look at statistics from the Department of Transport, they show driving too fast for the conditions accounts for only nine per cent of all accidents. The single biggest causes of accidents are driver or rider error, failure to look properly and failure to judge the approach of another vehicle. The latter two account for about half of all accidents.

"Speed is clearly some way down the list. It seems to us that speed cameras are only being used to raise revenue. We can't say that speed cameras will never prevent an accident, but they are a very blunt tool which mostly tend to catch people driving a little above the speed limit."

Avon and Somerset Police spokesman Martin Dunscombe said: "Mobile speed cameras are recognised by the police and our partners as offering the greatest flexibility in tackling excess speed and contributing towards safer roads. Their use can be targeted where it is needed most; at locations where there have been fatalities and injuries and where speeding is a concern for the community.

"There are still a minority of motorists who believe speeding is acceptable despite the views of the wider community.

"They risk the lives of pedestrians and road users and can seriously injure and kill people. Mobile speed cameras are a visible deterrent and allow us to identify speeding drivers."

He added that one in six fatal road traffic collisions could be attributed to the "fatal four": drink driving, mobile phones, speeding or failure to wear a seatbelt.