Confusion at the petrol pump has cost police forces in the West £55,768 since 2005, as staff continue to fill up vehicles with the wrong fuel.

That is the bill racked up in repair costs as engines in patrol cars, riot vans and motorbikes have been ruined by diesel or petrol being incorrectly used.

Police forces elsewhere in the UK hit the headlines earlier this year for their gaffes, but the Western Daily Press can now reveal for the first time where our constabularies have been going wrong.

Freedom of Information Act requests revealed since April 2005, 148 Avon and Somerset police vehicles have needed to be repaired because drivers have either been unaware of what fuel is needed, or have made a mistake.

This has cost £23,297.25.

Gwent police, which covers Monmouthshire, have made similar mistakes 88 times in the past three years, costing £16,137, while the figures for West Mercia, which covers Herefordshire, were 57 repairs at a cost of £10,736.

Dorset have had a better record, spending £5,098.02 on 28 vehicles, but setting a sterling example is Wiltshire police, which have put measures in place to make sure no more than £500 has been spent on the problem.

Their data protection and Freedom of Information officer Andy Holyoake said: "We have five cars that have had the wrong fuel put in them.

"The problems were reported immediately, the vehicle collected by our own recovery team and tanks drained and cleaned in the workshop.

"The cost to the force, excluding the minimal fuel lost, has been less than £500 (two hours labour x five vehicles x £38.40 per hour).

"We have experienced no damage to engines because the problems were sorted in good time.

"These incidents have occurred while drivers have used fuel cards at retail fuel stations."

And he explained how the problem has been almost completely solved, adding: "All our force vehicles have a Triscan fuel key, so a majority of fuelling is at our own sites. These Triscan keys are vehicle specific and programmed to only allow the driver to refuel with the correct fuel for that particular vehicle."

Scott Collington, temporary Freedom of Information officer for Dorset police, said: "Dorset Police has a fleet of 440 vehicles.

"A variety of measures, including audible warning devices and physical barriers, have been introduced during this period to minimise the risk of miss-fuelling.

"On our new vehicles, the opportunity to miss-fuel has been designed out and our performance is improving."

According to the AA, at least 150,000 drivers put the wrong fuel in their car each year – one every three and a half minutes.

The problem has been getting bigger, especially over the past five years with growth in diesel sales.

The AA said modern diesels are so quiet it can be easy to forget you are driving one, particularly if it is a second family car or a hire car. If a driver has put in the wrong fuel they are advised not to turn on the ignition as this will circulate the fuel, increase risk of damage and make any repairs more expensive.