BAGHDAD Executions by insurgents and death squads made up the biggest number of Iraqi civilian deaths in five years of war, while suicide bombers acting as "smart bombs" rivaled aerial bombs for deadliness, a study said.
The study conducted by King's College and Royal Holloway of the University of London, and non-profit group Iraq Body Count, found that of 60,481 civilians killed between March 20, 2003, and March 19, 2008, 33 percent were abducted and executed.
Of those executed in the study group, 29 percent bore marks of torture, such as bruises, drill holes or burns.
The most deadly events for civilians involved aerial bombings, which would have been carried out primarily by U.S. forces, and the combined use of ground weapons and aerial bombs, which both killed an average of 17 civilians per event.
But suicide bombings by sectarian or insurgent groups were almost as bloody, killing an average of 16 people in each event.
"A suicide bomber on foot acts as a precision weapon - a close quarters 'smart bomb' whose pattern of killing many civilians at a time can result only from either disregard for civilians when targeting opposition forces or direct targeting of civilians," the report found.
"When combatant forces intentionally target civilians, they commit a war crime."
After executions, small-arms gunfire in firefights and open shootings accounted for 20 percent of civilian deaths and suicide bombs for 14 percent.
Published in the April 16, 2009, issue of the New England Journal of Medicine, the study was based on a database of civilian deaths in Iraq maintained by www.iraqbodycount.org.
The database contains data on up to 99,774 civilian deaths that occurred after the March 2003 U.S.-led invasion of Iraq to topple Saddam Hussein. Iraq Body Count says its figure underestimates the true number of casualties.
The study excluded deaths that occurred during prolonged bouts of violence, such as long sieges by U.S. forces of insurgent-held areas, and deaths in which the type of weapon used was not reliably documented.
The invasion triggered a ferocious insurgency and a wave of bloodshed between Iraq's once dominant Sunni Arab minority and its majority Shi'ite Muslim population.
More than 4,000 U.S. troops have also died.
The report's authors said their findings about aerial bombs and the large number of civilian casualties they caused per event showed their use should be prohibited in civilian areas to comply with international laws.
(Reporting by Michael Christie; Editing by Sophie Hares)