Five Blackwater guards involved in the shootings will face trial in February
Iraq has ordered an investigation into whether the US security firm Blackwater paid bribes to officials following the fatal shootings of 17 people in 2007.
Interior Minister Jawad al-Bolani told CNN that he had asked the appropriate commanders to look into the matter.
The decision came after former top Blackwater executives told the New York Times they had sent $1m to its office in Iraq in a bid to silence criticism.
But the executives said they did not know if any payments had been made.
At the time of the incident, which occurred in Baghdad's Nisoor Square, Blackwater provided diplomatic security for the US embassy and needed a licence from the interior ministry to continue doing so.
The Iraqi government pressed Washington to withdraw Blackwater from the country, but the security firm's US contract was renewed in 2008. Despite being denied a new operating licence earlier this year, a subsidiary continues to provide air support for US diplomats in Iraq.
The former executives of Blackwater Worldwide, now renamed Xe, told the New York Times that the payments to interior ministry officials in an attempt to assuage their anger were approved by senior executives at the company in December 2007.
Two of the executives said they were directly involved in discussions about the bribes, while the other two said they were only told about them.
Talk of the payments, which would have been illegal under the US Foreign Corrupt Practices Act, caused a deep rift within the company, they added.
They said that when vice-chairman Cofer Black, a former top CIA and State Department official, learned of the plan from another Blackwater manager he confronted Erik Prince, the company's chairman and founder, who allegedly did not deny it. Mr Black resigned the following year.
Mr Black has denied that he had confronted Mr Prince "or any other Blackwater official regarding any allegations of bribing Iraqi officials and was unaware of any plot or guidance for Blackwater to bribe Iraqi officials".
Mr Jackson, who resigned as president earlier this year, criticised the newspaper when contacted and said: "I don't care what you write."
A spokesman for the company said it disputed the "baseless allegations" and would not comment on former employees.
Senior State Department officials have said diplomats were not aware of any bribes for Iraqi officials, but that they did support compensation payments to victims' families and survivors.
Speaking after the allegations were published, Mr Bolani said he had ordered senior interior ministry officials to look into them.
A Xe subsidiary continues to provide air support for US diplomats in Iraq
"My door is open to anyone with any complaints or information about this and I hope they provide me with any information that may help with the investigation," he told CNN.
"Blackwater is company which caused a major national tragedy. The Nisoor incident was a very difficult one and no-one can ever forget it. But the Iraqi government was committed and acted responsibly for the sake of the Iraqi people and for the reputation of Iraq," he added.
Five Blackwater guards involved in the Nisoor Square shootings are due to face trial on federal manslaughter charges in February in Washington. A sixth guard pleaded guilty in December.
Donald Ball, Dustin Heard, Evan Liberty, Nick Slatten and Paul Slough - all of whom are decorated military veterans - say they were acting in self-defence, but witnesses and family members of those killed maintain that the shooting on 16 September 2007 was unprovoked.
Iraqi investigators said the guards had fired their automatic weapons indiscriminately, and even launched grenades at a nearby school.
Afterwards, the Iraqi government described the guards as "criminals", and declared that Blackwater was a challenge to its sovereignty.