The device would allow ambulance staff to scan patients with a suspected stroke before they even arrive at the hospital, meaning life-saving treatment could be given immediately.

The scanner would be linked to a computer onboard the ambulance using Bluetooth wireless technology to help staff in their assessment.

It is being developed by Dr Alistair McEwan, from University College London, who has just been awarded a grant of almost pounds 140,000 by charity Action Medical Research.

The availability of new clot-busting drugs means that some stroke patients who are treated within three hours of their attack can make a full recovery.

But doctors need to be sure of the cause of the stroke, which can be due to either a bleed or a blood clot in the brain, before giving treatment.

In some instances giving patients the clot-busting drugs could make the damage to the brain worse.

At the moment patients have to have an MRI or CT scan to check what has caused their stroke.

But this can take up valuable time in hospital when every second counts to keep brain damage to a minimum.

Dr McEwan said that he hoped his quick-to-use portable system would help solve this problem, letting ambulance staff provide treatment.

Each year more than 130,000 people in England and Wales have a stroke and there are around 60,000 deaths.

Stroke is the largest single cause of severe disability in England and Wales