Motorists suspected of getting behind the wheel after taking cannabis or cocaine will be tested with a new roadside device.

The DrugWipe system allows officers to determine in less than 10 minutes whether motorists have the illegal substances in their body, using a swab from inside a driver's cheek.

Officers no longer need to prove that a motorist is fit to drive - just that the motorist has an illegal level of drugs in their system while driving.

Any drivers who fail the tests will be arrested and taken to a police station where they will be asked to consent to a sample of their blood being taken. That blood will then be sent away to be examined and if illegal levels of a drug are found, the motorist faces being prosecuted for drug-driving.

If the driver refuses to give consent, they face being prosecuted for the offence of failing to provide a sample of blood for analysis.

The system comes into force on March 2 following the introduction of new legislation that sets legal limits for how much of a substance – both legal and illegal – motorists can have in their system while driving.

The change in the law is designed to make it quicker and easier for drug-drivers to be prosecuted - meaning more of the dangerous motorists can be removed from the streets.

Illegal drugs covered by the new rules include cannabis, cocaine, ecstasy, heroin and ketamine.

Medicinal drugs covered include diazepam, methadone and morphine. The limits for these drugs have been set after advice from a panel of medical experts, at the level where the substances begin to affect driving.