Eating up to six bars of chocolate a week could reduce the risk of a potential heart condition by almost one quarter, a study by Harvard University suggests.

The research on more than 50,000 people found strong links between regularly eating the treat and a reduced risk of suffering a heart flutter.

The strongest association was found among men eating between two and six portions of chocolate a week - with a portion classified as 30g, which is a small bar.

Those doing so had a 23 per cent lower risk of developing atrial fibrillation, compared with those avoiding such treats.

Among women, the effect was linked to eating just one portion a week, which was linked to a 21 per cent lower risk.

But other experts said the group eating the least chocolate were unhealthier in other ways - meaning it might not be the daily treats that explained the better health of those who liked to indulge.

More than 1.5 million people in the UK suffer from atrial fibrillation, with one in four likely to develop it over a lifetime.

The condition, also known as a heart flutter, doubles the risk of dying from other cardiac conditions, including stroke, heart attacks and heart failure.