A new testing kit which will allow police to tell whether drivers are under the influence of drugs has been launched by an Oxfordshire firm.

The Drug Detection System will reveal whether people have been using drugs including cocaine, amphetamines or heroin, using a simple saliva test that takes moments to complete.

Experts at Cozart, based in Milton Park, near Didcot, say sampling typically takes 30 seconds.

Analysis of whether Class A drugs have been taken can be done in 90 seconds. Up to five drug types can be detected in five minutes.

Cozart managing director Philip Hand said: "We are particularly targeting roadside applications where it is important to process results rapidly."

The development builds on Cozart's existing technology the Rapiscan system, already in use for testing in police stations, and its powder testing kits, which have been used to test for cocaine use in pubs and clubs.

Mr Hand said the new system could also be used to test for drugs in the workplace and in drug rehabilitation clinics by medical professionals.

It has already been taken on by police in Australia for use at the roadside, following a number of studies.

The launch came after Cozart won a new £2m four-year contract from the Scenesafe arm of the Forensic Science Service, which carries out DNA testing of criminals for the police.

Cassie Shaw, head of Scenesafe, said: "Cozart's infrastructure, resources and ability to deliver were all key factors to our decision-making process"

Cozart, which also has bases in Spain and Sweden, employs 130 people, 75 of them at Milton Park.

It was set up by Mr Hand and his brother Chris in 1993, and floated on the Alternative Investment Market in July 2004, making them paper millionaires.

Mr Hand said the company was growing rapidly with turnover now reaching £1m a month.

Ten staff have been taken on in the last year.