A new study estimates that more than 1 million Iraqis have died because of the war in Iraq since the US-led invasion of the country in 2003.

Data compiled by London-based Opinion Research Business (ORB) and its research partner in Iraq, the Independent Institute for Administration and Civil Society Studies (IIACSS) reveals a fifth of Iraqi households lost at least one family member between March 2003 and August 2007 due to the conflict.

The study based its findings on survey work involving the face-to-face questioning of 2,414 Iraqi adults aged 18 or above, and the last complete census in Iraq in 1997, which indicated a total of 4.05 million households.

Respondents were asked how many members of their household, if any, had died as a result of the violence in the country since 2003, and not because of natural causes.

"We now estimate that the death toll between March 2003 and August 2007 is likely to have been in the order of 1,033,000," ORB said in a statement.

The margin of error for the survey was 1.7 per cent, making the estimated range between 946,000 and 1.12 million fatalities.

The highest rate of deaths throughout the country occurred in Baghdad, where more than 40 per cent of households had lost a family member.

According to a July 2007 estimate by the United States, Iraq's population is around 27 million.

The country has been racked by conflict since the March 2003 invasion, which deposed dictator Saddam Hussein, with United Nations estimates putting the number of displaced people from the conflict at more than four million, nearly half of which have fled to neighbouring countries.

A small number of those refugees have begun returning to Iraq. Earlier this month, the Iraqi Red Crescent said around 20,000 arrived from Syria in December, suggesting an improved security situation.

- AFP