The penalties for using a mobile phone while driving in the UK were increased as of midnight last night.
Department for Transport officials said that the previous penalty of a £30 fine was having little impact on drivers, 21 per cent of whom admitted breaking the law.
The fine has now been increased to £60 with an additional punishment of three points added to the licences of offenders.
In certain circumstances, where the case reaches court, ordinary drivers face a maximum fine of £1,000 and commercial drivers can be fined up to £2,500. Those found guilty could also be disqualified from driving.
Inspector Russell Clark, head of West Yorkshire Police's Roads Policing unit, said: "Not only is it illegal to use a mobile phone without a proper hands-free kit while driving, it is extremely dangerous.
"Being engaged in a conversation on the phone or sending and receiving text messages cause motorists to lose concentration, and greatly increases the risk of an accident."
The revised law also means that motorists can be prosecuted for using a hands-free kit if they are not in control of their vehicle. Authorities are encouraging people to switch off their mobile phones entirely when getting to the car.
"Drivers need to remember that they are always responsible for the proper control of their vehicle and can expect to be prosecuted if they are not," said Clark.
"While it is a specific offence to use a handheld mobile phone, a driver may not be in proper control of their vehicle while using a hands-free kit.
"I would encourage drivers to turn off their phone when they get into a vehicle and plan their journey and to have a safe place to stop in order to take messages and make calls."
Road safety campaigners have welcomed the changes, but are still calling for an outright ban of hands-free kits.
Police forces have warned that they will be cracking down on offenders.
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