The Cabinet has approved a new road traffic bill to strengthen the law on drug driving.

Minister for Transport Paschal Donohoe wants to create a new offence of driving with the presence of cannabis, heroin or cocaine in the blood.

At the moment, motorists who use drugs can be prosecuted only if their driving is impaired.

The new legislation allows gardaí to test the saliva of motorists at the side of the road, and positive indications will be followed up by blood test to confirm the presence of drugs.

The new offence will carry a €5,000 fine or six months in prison.

The bill also creates a new option for local authorities to impose a special speed limit of 20km/h in built-up areas, and would give effect to an agreement with the UK on mutual recognition of driver disqualifications.

Speaking on RTÉ’s Morning Ireland, Mr Donohoe said there is growing evidence that some people who have died on Irish roads died with drugs in their system.

Evidence has found that over a ten-year period, 10% of road users who died had used drugs.

The minister also noted that there will be a separate test for prescription drugs to see whether they impair driving.

He said that prescription drugs, if used properly, should not affect driving.

Mr Donohoe said that great care had been taken in putting the legislation together, that this kind of road traffic law has been enforced in many other jurisdictions, and that his department has carefully monitored how it has worked in other countries, such as the UK.