However, he team, from Geneva University Hospital, said smoking cannabis did not produce the same effect. British experts warned more research was needed before firm conclusions could be drawn.

Blocked arteries - a condition known as atherosclerosis - are estimated to be responsible for up to 50% stroke and heart disease deaths in developing countries each year.

In the study, published in the journal "Nature", mice were fed a high cholesterol diet to make them develop atherosclerosis and then given THC, which causes the high during cannabis use. The Swiss researchers found THC stopped inflammation of blood vessels, which is largely responsible for blocking arteries.