The device will enable screening of suspects at police stations, removing the need to call out a doctor. If the screening is positive, a blood sample will be taken straight away for evidential testing. This should reduce the waiting time before evidential samples are taken, helping to ensure that any drug levels are recorded before they dissipate.

'Motorists under the influence of drugs are a danger on the road,' said crime prevention minister James Brokenshire.

'We are determined that police have the highest quality devices to help identify them. This specification is a big step towards that goal.

'Police already have robust powers to test drivers for signs of impairment and this device will make it easier for them to identify the reckless drivers who are putting lives at risk.'

Ellen Booth, Brake's campaigns officer, said: 'This is definitely a step in the right direction, but we're not there yet. Provisions to tackle drug driving have been woefully inadequate for too long – other countries are leaps and bounds ahead of us. There still isn't a law making it an offence to drive on illegal drugs. Without this legislation, the police have to try to prove driver impairment, which is difficult and helps to explain why there are so few convictions. We need a roadside drugs screening device, and high levels of random testing, so that drivers know there is a significant chance of being caught.'

She added: 'I sincerely hope this signals the Coalition's intention to act swiftly on drug driving and implement further changes that are desperately needed to stamp out this deadly menace on our roads.'