Social factors rather than genetics are blamed for the huge gaps in health and life expectancy.

The issue has been the focus of a three-year investigation by the World Health Organisation's Commission on the Social Determinants of Health.

Their findings were presented yesterday to WHO director-general Margaret Chan.

''Health inequity really is a matter of life and death,'' Dr Chan said.

''But health systems will not naturally gravitate towards equity. Unprecedented leadership is needed that compels all actors, including those beyond the health sector, to examine their impact on health.''

The commission concluded that social injustice was ''killing people'' on a grand scale.

Health inequalities had long been measured between countries.

But the commission documented ''health gradients'' within countries, including in Australia, where indigenous people were likely to die 17 years earlier than their non-indigenous counterparts.

The commission hailed the Australian Government's apology to the Stolen Generations as ''recognising the unique history of colonisation on indigenous peoples and the need for special measures''.

One of the commissioners, Australian professor Fran Baum, said it was easy to blame people's behaviour for their health problems.

''If people stopped smoking or stopped eating junk food, they'd be healthy,'' she said.

The problem was more complex and the report was a ''major wake-up call''.

''The main message is that health inequities affect all of us,'' Professor Baum said.

''The evidence is we can do something about them by changing the structures the way that we organise our social policies, our health policies ... our cities, food supply ... and work.''

The commission made overarching recommendations to deal with ''the corrosive effects of inequality''.

Governments must improve daily living conditions, including the circumstances in which people are born, grow, live, work and age.

Countries should also tackle the inequitable distribution of power, money and resources.

''It's a landmark report because it's saying, first and foremost, that this is a social justice issue and it's saying that governments have a responsibility to promote health,'' Ms Baum said.

''We're saying it would be possible to have every citizen of the world living roughly the same length of life there are obviously some genetic and biological issues within about 25 years.'' Ms Baum said critics would be wrong to dismiss the commission as a ''bunch of idealists''. ''I think we're actually quite realistic,'' she said.

''It's like most things. People used to think votes for women were silly. They use to think abolishing slavery was silly. We think one day people will say 'Imagine they used to live with those huge health inequities and now we don't'.''