Texting while driving impairs motorists more than being under the influence of drink or drugs, research suggests.

The RAC Foundation found average reaction times slowed by 35% when 17 to 24-year-olds drove in a simulator while writing or reading texts.

Nearly 50% of drivers aged between 18 and 24 texted while driving, it said.

Previous studies had found reactions were 21% slower among those who had taken cannabis and 12% slower among those who had drunk to the legal limit.