The first mobile drug-testing device has been approved by the Government for use on drivers suspected of being under the influence.

The device known as Drugwipe is the first portable device that can detect the presence of cannabis and cocaine - two of the most common substances used by drug drivers - by analysing a small quantity of saliva.

Results are indicated by the appearance of lines on the device - similar to a pregnancy test - within eight minutes.

Policing Minister Mike Penning, who announced the device's approval at a road policing conference, said: " Drug drivers are a deadly menace and must be stopped.

"It has long been my ambition as Roads Safety Minister and now as Minister for Policing to take further action on drug driving.

"Those who get behind the wheel while under the influence of drugs not only put their own lives at risk, but also those of innocent pedestrians, motorists and their passengers."

Following a positive reading, the police will take the individual to the police station for a blood sample, which will b e used in any subsequent prosecution.

It is estimated as many as 200 people a year are killed by drivers impaired by drugs.

Drugwipe will be used to enforce the existing offence of driving whilst impaired as well as a new drug driving offence set to come into force in March.

The penalty under the new offence will be 12 months disqualification, a fine up to £5,000 and up to six months in prison or both.

The new law sets limits for eight illegal drugs - cannabis, cocaine, ecstasy and ketamine, heroin, lysergic acid diethylamide, methylamphetamine and MDMA - at very low levels.

AA president Edmund King said: "We have known for a long time that drug-driving kills around 200 people every year on UK roads.

"To tackle this needless waste of life, the police need to be able to test drivers accurately for drugs and we need tough legislation in place to prosecute those who are found to be drug-driving.

"The approval of drug-testing devices is certainly a move to be welcomed. Any driver who has taken the risk of drug-driving in the past should take this as their final warning that drug-drivers will not be tolerated on our roads."