Drivers using a mobile phone were involved in crashes which killed the equivalent of one person every 10 days last year, new figures show.
Some 35 deaths were recorded in accidents where a driver being distracted or impaired by their phone was a contributory factor in 2016, up from 22 the previous year.
A further 137 road users were seriously injured in such incidents, according to the Department for Transport data.
Motoring groups have led calls for illegal phone use to be tackled after a string of high-profile cases and research indicating the problem is widespread.
Steve Gooding, director of the RAC Foundation, said: ‘Even this big rise in fatalities is likely to be an under-reporting of the true scale of the problem which can be difficult for police to detect.
‘It seems too many drivers still can’t resist picking up the mobile whilst at the wheel.
‘Forget all the technological solutions, the best ‘drive safe’ mode is reached via one click of the power-off button.’
Apple’s new iPhone includes a function which silences notifications and turns off the screen when it detects a user is driving.
Since March 1, drivers who use a hand-held phone have faced receiving six points on their licence and a Â£200 fine – up from the previous penalty of three points and Â£100.
Figures obtained by the Press Association revealed that more than 200 drivers a day were caught using their mobile phones illegally in the four weeks after the changes took effect, equivalent to one every seven minutes.