New drivers face losing their licence the first time they are caught using a phone behind the wheel illegally.
Penalties and fines for offenders will be doubled to six points and £200 respectively from today.
The new measures are being introduced following a series of high-profile cases and research suggesting the practice is widespread.
New drivers can have their licence revoked if they get six penalty points in their first two years on the road, which could now be the result of sending a single text message.
More experienced motorists can lose their licence if they receive 12 points in a three-year period.
Twenty-two people were killed and 99 seriously injured in accidents on Britain’s roads in 2015 where a motorist using a mobile was a contributory factor, latest figures show.
Transport Secretary Chris Grayling said increasing fixed penalties will be a “strong deterrent”.
He added: “Everyone has a part to play in encouraging their family and friends not to use their phones while driving. It is as inexcusable as drink driving.”
The Department for Transport said members of the public can report repeat offenders anonymously by calling Crimestoppers on 0800 555111.
Police forces are carrying out a seven-day crackdown with extra patrols and an “increased focus” on catching drivers using handheld phones.
Around 3,600 motorists were handed penalties during a similar initiative last month.
According to the Transport Research Laboratory, reaction times are twice as long for drivers who are texting compared with those who have been drinking.
A new advert developed by the Government’s road safety group Think! and the AA Charitable Trust shows a drunk man suggesting he should swap places with his sober girlfriend, who is texting on her phone while driving him home.
The campaign will be featured at cinemas and on billboards, radio and social media, with the message: “You wouldn’t drink and drive. Don’t text and drive.”
AA president Edmund King said too many motorists are “addicted” to their phones, with half of young drivers unable to bring themselves to switch them off before starting a journey.
“We need to break this addiction and the best way is for drivers to go cold turkey - turn off the phone and put it in the glove box,” he added.
Breakdown firm the RAC is urging motorists to pledge not to use their phones while driving on its new BePhoneSmart.uk website.
RAC road safety spokesman Pete Williams said encouraging motorists to take personal responsibility for their actions must be at the heart of the campaign to change driving habits.
Motoring groups believe a sharp decline in the number of offenders caught is partly due to police budget cuts affecting enforcement.
An RAC survey found that one in four (26%) motorists admits checking texts, emails and social media while driving.
Lorry driver Tomasz Kroker was jailed for 10 years in October after killing a woman and three children by ploughing into their stationary car on the A34 near Newbury, Berkshire, while distracted by his phone.
Inspector Rich Champion said: “Despite the wide known fact that the use of mobiles whilst driving has been illegal for a number of years now, we still see drivers distracted by phones.
“In recent years there have been a number of fatal collisions involving drivers using mobiles.
“Families have been left mourning the loss of a loved one, all because someone deemed accepting a call or checking social media to be more important than road safety.”