The findings are based on a study involving almost 19,000 patients worldwide.

The doctors found that lowering diastolic pressure from an average of 105mm of mercury to 83mm could cut the risk of both strokes and heart attacks by 30%.

Diastolic pressure is the point where blood pressure falls between heartbeats, and is normally about 80mm in a healthy adult.

Risk halved

Patients with high blood pressure and diabetes had their risk of heart attacks and strokes halved.

According to the findings, optimal treatment could prevent five to 10 heart attacks or strokes per 1,000 patients each year.

The Hypertension Optimal Treatment (HOT) research, based at Ostra Hospital, the University of Gothenburg, Sweden, took six years.

Patients with an average diastolic blood pressure of 105mm in 26 countries took part.

Dr Gordon McInnes, consultant physician at the Western Infirmary, Glasgow, and a member of the HOT study steering committee, said: "The findings of the HOT study have important implications for patients with hypertension (high blood pressure), many of whom are currently receiving inadequate treatment.