They claimed that strategies to reduce long-term sick leave should involve education.

''Our findings suggest that health is only one factor in understanding long-term sickness absence.

"We suggest that education should form part of the policy response to long-term sickness absence: for future generations, equipping children with skills necessary for labour market flexibility may inoculate them from the risk of long-term sickness absence,'' they wrote.

According to the study low cognitive ability and/or educational attainment is ''likely'' to limit the ability to transfer skills. It gives the example of a person with few skills who goes off sick from a labouring job having few options to find alternative employment.

The report, written by experts including Max Henderson of King's College London, concluded: ''Long-term sick leave is a complex outcome with many risk factors beyond health.

''Cognitive abilities might impact on the way individuals are able to develop strategies to maintain their employment or rapidly find new employment when faced with a range of difficulties.''