New studies say more than a third of people have high blood pressure but many are unaware they have it.

The global report found 34.5 per cent of those studied worldwide had elevated blood pressure (above 140/90mmHg).

Of those, 17 per cent were not receiving treatment and 46.3 per cent were receiving treatment but still had uncontrolled blood pressure.

Blood pressure is the biggest killer world-wide, accounting for more than 10 million deaths each year.

The researchers analysed data collected from 1.2 million of people aged 18 and older across 80 countries.

“What’s really alarming is that almost half of the people who were already being treated for hypertension still had blood pressure above recommended levels. In other words, half of the world’s high blood pressure patients are inadequately treated,” said Australian researcher Professor Markus Schlaich.

“This is despite the availability of numerous blood pressure lowering medications and is largely due to people not taking the medication because they have had side effects or worry that they will have side effects.”

The study has been published in the medical journal LANCET Global Health.