Men who do not openly express their anger if they are unfairly treated at work double their risk of a heart attack, Swedish research suggests.

The researchers looked at 2,755 male employees in Stockholm who had not had a heart attack when the study began.

They were asked about how they coped with conflict at work, either with superiors or colleagues.

The researchers say their study shows a strong relationship between pent-up anger and heart disease.

Writing in the Journal of Epidemiology and Community Health, the researchers called the various strategies for keeping things bottled up, covert coping.