Eight in ten drivers admit getting distracted when driving, a potentially lethal situation that also cost them hundreds of pounds in increased insurance costs, a research reveals.

According to a study carried out by Moneysupermarket.com, motorists face considerable increases in their car insurance premiums if they are caught driving carelessly.

It is not only the £60 fine and three penalty points on the licence drivers have to face when convicted of driving without due care and attention: there is an increase of between £200-400, an average of 27%, in their car insurance premiums.

The leading causes of distractions are smoking, changing the radio station and slowing down to look at accidents, the comparison site says, and a charge can be brought against a motorist for doing something as apparently innocuous as eating a sandwich while driving.

"Although it may be unintentional, careless drivers are a menace on the roads and are a danger to both themselves and others. Not only are these bad driving habits, but also expensive habits if you are caught," said Peter Harrison, car insurance expert for Moneysupermarket.com.

To establish an offence for careless driving is sometimes a tricky question. The prosecution must prove that the motorist is at fault and that the standard of their driving fell below that of a competent and careful driver.

These cases are often determined on the basis of one person's evidence against that of another and the situation requires detailed cross-examination of available eye witness versions to establish the facts.

It is an offence for a person to drive on a road or other public place without due care and attention or without reasonable consideration for other persons using that road or place.

Among the 16,500 motorists convicted every year, newly qualified drivers are particularly hard hit. They have seen premiums double over the last twelve months, which makes it very difficult to find affordable cover.

There are considerable differences between a clean license and one with a careless driving conviction, depending on the insurance company. According to the survey, Axa charges £603.53 clean and £1,006 after a conviction, Churchill charges £867.08 before and £1,239 after, while Swiftcover asks for £640 before and £806 after.