More than 200 drivers a day were caught using their mobile phones illegally in the wake of a major crackdown on the practice.
Police forces in Britain penalised almost 6,000 motorists for the offence in the four weeks after tougher punishments took effect, equivalent to one every seven minutes, figures obtained by the Press Association reveal.
Campaigners claimed the "worrying" findings suggest many drivers are ignoring repeated warnings about the dangers of using phones at the wheel despite a string of publicity campaigns and the risk of harsher sanctions.
From March 1, those who fall foul of the rules have faced receiving six points on their licence and a £200 fine - up from the previous penalty of three points and £100.
The changes mean new drivers risk losing their licence for sending a single text.
Calls for efforts to curb illegal mobile phone use intensified in the wake of a string of high-profile cases and research indicating that it is widespread.
Figures obtained following Freedom of Information requests show forces recorded 5,977 instances of the practice the four weeks after the clampdown was rolled out alongside a nationwide police campaign.
The actual figure is likely to be higher as seven forces did not provide figures and some cases may not have been logged at the time FOI responses were issued.
The Metropolitan Police registered the highest number at 2,037, meaning more than 70 drivers were caught using a handheld phone on London's roads each day.
Thames Valley Police recorded the second-largest total at 478, followed by Police Scotland (339), Hampshire Police (280) and Cheshire Police (224).
Incidents reported by police after the tougher penalties were introduced include:
:: A man was spotted doing his online banking while driving along the M5 motorway near Birmingham
:: Norfolk Police stopped a woman who was responding to a message about her lost puppy being found
:: A foreign lorry driver was fined for texting on a bright pink mobile phone while travelling along the M2 in Kent
:: A 7.5-tonne lorry was driven around a roundabout in Bournemouth by a man using his phone
:: A driver was on his phone while behind the wheel of a school minibus with 10 children on board in Manchester
The RAC Foundation described the increased penalties as "a start", but warned the figures for March suggest "the key message still isn't sinking in".
Steve Gooding, director of the motoring research charity, said: "Driving is a safety-critical activity that requires our full attention. Hands need to be on the wheel and eyes looking out of the windscreen, not down at the phone screen."
The new figures sparked calls for more investment in traffic policing to compliment the tougher penalties.
There have been falls in the numbers of drivers handed fines for using handheld mobiles in recent years amid reductions in full-time dedicated roads policing officers.
Brake spokesman Jack Kushner described the number of drivers "selfishly using their mobile phones behind the wheel" as concerning.
"Driver distraction is a growing menace and it's worrying that drivers don't seem to be getting the message," he said.
The charity wants the £200 fine to be "significantly increased" to deter offenders.
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, Department for Transport figures show.
Police say they want to make using a mobile while driving as "socially unacceptable" as drink-driving.
National Police Chiefs' Council lead for roads policing Anthony Bangham said: "Drivers need to understand that this is not a minor offence and you will be prosecuted under new, tougher penalties."
He said forces are committed to tackling the behaviour, adding: "Encouraging results from recent campaigns show how effective new tactics and innovative approaches can be."