US military commanders in Iraq today ordered ethics training for combat troops after accusations that marines murdered unarmed civilians in an Iraqi town last year.
Iraqi Prime Minister Nuri al-Maliki demaded investigations into Haditha and other cases of alleged US military killing of civilians
The training over the next 30 days in "core warrior values" would highlight "the importance of adhering to legal, moral and ethical standards on the battlefield," a statement said.
US defence officials have said murder charges may be brought against marines following an investigation into the deaths of 24 civilians in Haditha in November.
Many Iraqis believe unjustified killings by US troops are common, although few have been confirmed by investigations.
Echoing comments by President Bush this week, a senior US military spokesman said anyone guilty of violations against civilians would be punished.
He said that apart from Haditha, a stronghold of the Sunni Arab insurgency, the US military was investigating three or four other cases, but did not specify.
The military statement did not mention events in Haditha, which some commentators are comparing to the 1968 My Lai massacre in Vietnam that helped turn many Americans against that war.
Iraq's new prime minister Nuri al-Maliki said this week he wanted investigations into Haditha and other cases. In an interview on Tuesday he said his patience was wearing thin with excuses that US troops kill civilians "by mistake".