Research by the RAC reveals a third of motorists (31 per cent) admitted to making or receiving a call on a handheld phone in the last 12 months.
Extrapolated across the country, that means an estimated 11 million drivers breaking the law.
The group is now calling for an awareness campaign to highlight the dangers of using a handheld device at the wheel as well as urging better enforcement of the law and backing plans for harsher penalties.
The survey of 1,714 drivers for the RAC Report on Motoring also found that a quarter of drivers admitted checking messages while driving and nearly 1 in 5 (19 per cent) said they had written and sent texts, emails or social media posts while on the move.
These figures rose dramatically when the driver was in stationary traffic with 46 per cent admitting they check messages and 38 per cent admitting they had written texts, emails or posted social media updates.
The survey also found that 14 per cent had taken photos or videos while driving, with younger drivers being even worse offenders - 36 per cent of 17 to 24-year-olds admitted to the offence
Worryingly, the data shows that attitudes to using handheld phones while driving have softened.
The proportion of people who feel it is acceptable to take a quick call on a handheld phone has doubled from 7 per cent in 2014 to 14 per cent in 2016.
Releasing the figures the RAC said: “The evidence is irrefutable that using a handheld mobile phone is a major impairment to driving, and is both a physical and a mental distraction that can result in accidents and even fatalities.”
RAC road safety spokesman Pete Williams said: “There is clear evidence that the illegal use of handheld phones by drivers to talk, text, tweet, post, browse and even video call is, if anything, on the increase.
“The use of handheld mobile phones is the biggest road safety concern among motorists today, and while the Government is progressing the introduction of stiffer penalties, we call on all stakeholders to step up efforts to shift cultural attitudes and make the use of handheld mobiles phones as socially unacceptable as drink-driving.
“With compliance on some traffic laws including the use of handheld mobile phones seemingly getting worse, the RAC calls for an end to cuts to dedicated roads policing and urges the Government and chief constables to give greater priority to enforcement of road traffic laws.
“The RAC is also calling on the Government to invest in a high profile awareness campaign to highlight the danger of using a handheld phone at the wheel and to drive home the message that it simply won’t be tolerated.