Teenage drivers are three times as likely to have a fatal crash if they are travelling with a group of friends as when driving alone, a study has found.

The greatest danger is posed during the first 30 weeks after passing their test. After that, the risk that they will cause a death or serious injury on the road is cut by half.

The Association of British Insurers , which publishes the findings in a report today, is urging the Government to introduce restrictions on young drivers for six months after they qualify.

The association says that 270 deaths or serious injuries a year would be prevented by a law limiting drivers aged under 20 to carrying no more than one teenage passenger for the first six months after they qualify.

The Department for Transport has acknowledged the evidence of benefits from placing conditions on the licences of young drivers. Several US states have limited the number of passengers a teenage driver can carry in the first six or 12 months: on average, fatal crashes fell by 37 per cent after the limits were introduced.

The report from the association says that the collision rate for young drivers increases with each additional passenger carried. Compared with driving alone, the risk of a fatal collision for young drivers is 39 per cent higher with one passenger, 85 per cent higher with two and 182 per cent higher with three or more. Overall, teenage drivers are twice as likely as those aged over 30 to kill or injure passengers.

The department is focusing on making the driving test more rigorous and has doubts about the practicality of restrictions that require police to determine the age of passengers. However, Nick Starling, of the insurers’ association, said: “Government proposals will not reduce significantly the unacceptable casualty rate among young drivers and their passengers.

"We want a six-month limit on the number of teenage passengers, which will result in far fewer tragedies."

The association said the limit would reduce the cost of insurance for teenage drivers because the number of multimillion-pound claims would fall.