People who smoked even one cigarette a day were still about 50% more likely to develop heart disease and 30% more likely to have a stroke than people who had never smoked, researchers said.

It showed there was no safe level of smoking for such diseases.

Smokers need to quit cigarettes rather than cut back on them to significantly lower their risk of heart disease and stroke, a large BMJ study suggests.

An expert said people who cut down were more likely to stop.