Prohibitionists are grasping at straws by claiming that cannabis is linked to strokes, Norml president Julian Crawford says.

In the Auckland University study, all but one of the stroke patients who were cannabis users also used tobacco regularly.

According to the US National Stroke Association, "Smoking tobacco doubles the risk for stroke when compared to a non-smoker. It reduces the amount of oxygen in the blood, causing the heart to work harder and allowing blood clots to form more easily."

"Prohibitionists are scraping the bottom of the barrel by claiming that cannabis doubles the risk of stroke, when this result has already been linked to tobacco use," Mr Crawford said.

"There is nothing scientific about this study and it should be discredited by all rational individuals."