Heart failure is a hidden killer costing the NHS £625m a year and more must be done to tackle the problem, Oxford researchers have warned.

Scientists at the British Heart Foundation (BHF) Health Promotion Research Group, based at Oxford University's Department of Public Health, said heart failure deaths were falling, but the figure for people treated with the disease had increased over the past two decades.

To coincide with the launch of Heart Week this week, the charity warned that action needed to be taken to raise awareness of heart failure and improve diagnosis and treatment.

In their report, Coronary Heart Disease Statistics: Heart Failure Supplement 2002, the researchers show there are more than 878,000 UK sufferers.

And an ageing population means the number of hospital admissions with the condition is likely to increase by half in the next 25 years. But a recent national poll, also released by the BHF, showed that the general public were complacent about the danger.

It found that only five per cent of over-45 year-olds were worried about developing heart failure.

Only one in five people could accurately describe heart failure as a condition caused when the heart muscle becomes damaged, often after a heart attack, and less efficient at pumping blood.

More than half thought heart disease was a "quick way to go", but the charity said many sufferers experience a long and debilitating illness.

BHF medical director Prof Sir Charles George said: "We hope that Heart Week will drive heart failure up the social and medical agenda.

"There is an urgent need for greater understanding of heart failure and the enormous burden it is placing on patients, healthcare and the economy. More must be done to improve diagnosis and treatment of heart failure, to improve the quality of life of heart failure patients and to reduce the pressure on hospitals."