Texting while driving is riskier than driving under the influence of alcohol or drugs, a study has suggested.

The Transport Research Laboratory found that motorists who use their mobile phone to send text messages while on the road dramatically increase the likelihood of collision.

Their reaction times deteriorated by 35 per cent, much worse than those who drank alcohol at the legal limit, who were 12 per cent slower, or those who had taken cannabis, who were 21 per cent slower.

In addition, drivers who sent or read text messages were more prone to drift out of their lane, the research found, with steering control by texters 91 per cent poorer than that of drivers devoting their full concentration to the road.

This compared with a decline of 35 per cent by drivers under the influence of cannabis. The ability to maintain a safe distance from the vehicle in front also fell.

Stephen Glaister, director of the RAC Foundation, which commissioned the research, said: “No responsible motorist would drink and drive. We need to ensure that text devotees understand that texting is one of the most hazardous things that can be done while in charge of a motor car.”

Despite it being illegal for a motorist to use a handheld phone behind the wheel, the RAC Foundation said that nearly half of British drivers aged between 18 and 24 admitted to texting on the roads. Yet only 144,000 people were prosecuted for using their mobile while driving last year.

During the study, the Transport Research Laboratory concluded that text messages took on average 63 seconds to compose while the phone owner was driving, compared with 22 seconds when sent from a desk.

In one minute, a car travels half a mile at town centre speeds and more than a mile on the motorway.

Nick Reed, lead researcher for the study, said: “This demonstrates how dangerous it is to drive and text. When texting, drivers are distracted by taking their hand off the wheel to use their phone, by trying to read small text on the phone display and by thinking about how to write their message.

“This combination of factors resulted in impairments to reaction time and vehicle control that place the driver at greater risk than having consumed alcohol to the legal limit for driving.”

The Department for Transport said: “Driving and mobile phones don’t mix. That is why we increased the penalty for illegally using a mobile when driving to three penalty points and a £60 fine and have run hard-hitting campaigns to remind drivers of the dangers of using a phone in any way by encouraging them to ‘Switch off before you drive off’.”

Last month the law changed so that motorists who cause a fatal accident while using a mobile phone can be jailed for up to five years. Previously the maximum punishment for similar crimes was a £5,000 fine and points on the driver’s licence.

It's very easy to lose the plot

Vodka is not a good idea if you are about to get behind the wheel. But yesterday The Times knocked one back and climbed into a Honda Civic.

Stationary in the Transport Research Laboratory at Wokingham, Berkshire, the vehicle simulated driving conditions: I wanted to know whether texting while driving is more distracting than drink-driving. Motion sensors and computer graphics created a realistic motorway route.

Just within the drink-driving limit, I stuck to the middle lane, worried about veering off. I noticed once or twice that I had exceeded the speed limit. I had previously done the course sober but texting on a mobile. I drifted out of my lane, and was surprised to see cars coming up from behind. Sometimes my foot came off the accelerator when I typed a message.

Nick Reed, of the laboratory, said: “When people are texting, they tend to be aware of the impairment to their driving but not aware how great that is. With alcohol, the driver is not aware of the impairment. You had misplaced confidence when you had had a drink and were often up to 80mph. When you were texting, you were wandering across the lane. And your reaction times were slower.

“You understood that drink-driving is a serious risk but had less understanding about the dangers of texting.”