Stroke victims are more likely to make a better recovery if they are given a new clot-busting drug, Scottish researchers said.

More than 3,000 patients worldwide took part in Edinburgh University's trial of the rt-PA drug, which was administered after an acute ischemic stroke.

Doctors found that for every 1,000 patients treated with the drug within three hours of stroke, 80 more will survive and live without help from others than if they had not been given the drug.

Professor Joanna Wardlaw, from the University of Edinburgh's Centre for Clinical Brain Sciences, said, "We have looked at data from more than 7,000 stroke patients worldwide. What we see is that the drug increases patients' longer term recovery."

However, patients are also at risk of death within seven days of treatment because the drug can cause a secondary bleed in the brain.

Wardlaw added, "We need to find out why some people bleed and how to reduce this to increase the effectiveness of clot busting treatment."

The findings, published in The Lancet medical journal, advised that the drug was effective up to six hours after a stroke.