Iraq will file lawsuits in US and Iraqi courts against Blackwater, a private security firm, after an American court threw out charges against five of its guards accused of killing 14 civilians in Baghdad.
Making the announcement, Nuri al-Maliki, Iraq's prime minister, in a statement on Monday said his government "rejects the ruling issued by the American court acquitting the company of the crime of killing a number of citizens".
Last week, a US federal judge threw out the murder charges against the guards, saying prosecutors violated the defendants' rights by using incriminating statements they had made under immunity during a US State Department probe.
The guards, who had been part of a convoy of armoured vehicles, had been charged with killing 14 unarmed Iraqi civilians and wounding 18 others in September 2007 at a busy Baghdad roundabout using guns and grenades.
But the guards claimed they acted in self-defence after a convoy they were protecting near Nisour Square came under attack.
However, witnesses and victims say the guards shot indiscriminately.
The Iraqi government called the US court ruling "unacceptable and unjust" and promised to support a lawsuit in US courts filed by victims of the shooting or their relatives.
Blackwater pulled out of Iraq in May, after the US state department refused to renew its contracts.
The company changed its name to Xe Services last year.