A simple blood test could predict if a person is likely to die - even if they are not ill.

Researchers said they were astonished to discover the "death test", which predicts the chance of a healthy person dying from a medical condition within five years.

They found that the levels of four "biomarkers" in the body, indicated a general level of "frailty". People whose biomarkers were out of kilter were five times more likely to die within five years of the blood test.

"What is especially interesting is that these biomarkers reflect the risk for dying from very different types of diseases such as heart disease or cancer. They seem to be signs of a general frailty in the body," said Dr Johannes Kettunen of the Institute for Molecular Medicine in Finland.

"In the future these measures can be used to identify people who appear healthy but in fact have serious underlying illnesses and guide them to proper treatment."