Domestic violence, mainly against women and children, kills far more people than wars and costs the world economy more than $8 trillion a year, a new study suggests.

The authors of the report, released on Tuesday, said it was a first attempt to estimate global costs of violence and urged the UN to pay more attention to abuse at home.

"For every civil war battlefield death, roughly nine people are killed in inter-personal disputes," said Anke Hoeffler of Oxford University and James Fearon of Stanford University, who wrote the for the Copenhagen Consensus Centre.

From domestic disputes to wars, they estimated that all violence worldwide cost $9.5 trillion a year, mainly in lost economic output - and equivalent to 11.2 percent of world gross domestic product.

Civil wars cost the world economy about $170bn a year.

Illegal killings, mainly of men unrelated to domestic disputes, cost $650bn.

But those figures were dwarfed by the $8 trillion annual cost of domestic violence, mostly against women and children.

The study said about 290 million children suffer violent discipline at home, according to estimates based on data from the UN children's fund, UNICEF.

Based on estimated costs, ranging from injuries to child welfare services, the study estimated that non-fatal child abuse sapped 1.9 percent of GDP in high income nations and up to 19 percent of GDP in sub-Saharan Africa where severe discipline was common.

Bjorn Lomborg, the head of the Copenhagen Consensus Centre which commissioned the report, said household violence was often overlooked, just as car crashes attracted less attention than plane crashes even though many more died in road accidents.

"This is not just about saying 'this is a big problem'. It's a way to start finding smart solutions."

The centre draws on work by more than 50 economists, including three Nobel Prize winners, and looks at cost-effective ways to fight everything from climate change to malaria.

The study is meant to help the UN design targets for 2030 to succeed Millennium Development Goals set for 2000-15 that included curbing poverty and improving water supplies.