Blackwater, one of the largest American security firms in Iraq, has come under criticism in the US for its role in a 2004 ambush in Fallujah that left four of its staff killed and the region in deadly chaos.
A House of Representatives report outlined the "unprepared and disorderly" build-up to the incident on 31 March, 2004, resulting in the employees – who were escorting a convoy – being executed and having their charred bodies hung from a bridge.
The disturbing attack was seen as a turning point for US public opinion after images of the charred bodies were shown around the world by the media. A few days later, the US military launched a major offensive in Fallujah, leading to one of the bloodiest periods since the 2003 invasion.
Yesterday's report, led by the Democrat Representative Henry Waxman, said Blackwater had ignored "multiple warnings" to stay away from Fallujah, described as "hottest zone in Iraq in unarmoured, underpowered vehicles."
Although Blackwater – one of the biggest security firms in Iraq – was warned by other contractors that it was dangerous to drive through Fallujah, the Blackwater guards "seemed unaware of the potential risk," the report says. Two members of the mission's team were cut prior to its departure, the report found.
Blackwater – also under investigation for the deaths of 11 Iraqis this month, in an incident reported by The Independent – rejected the report, accusing it of being a "one-sided version of this tragic incident".
But Mr Waxman said the committee's research showed that the company was in a chaotic state in the run-up to the incident and "mistake apparently compounded mistake".
On 16 September this year, 11 Iraqis were killed after Blackwater guards opened fire while escorting a convoy through Baghdad. The company is under a joint US-Iraqi investigation over the incident.
John Negroponte, the Deputy Secretary of State and a former ambassador to Iraq, told Congress: "Something went tragically wrong on 16 September and we are taking steps to address the matter."
He added in a statement that from January this year until 18 September, Blackwater conducted 1,873 missions protecting diplomats or visitors outside of the Green Zone in Baghdad – 56 of which saw weapons fired by the firm.
The findings come as a fresh leaked transcript of a conversation between President Bush and his Spanish counterpart President Aznar before the invasion of Iraq in February 2003 show Mr Bush saying: "We have to get rid of Saddam. In two weeks we will be ready militarily. We will be in Baghdad at the end of March",
The comments – which appear to show disregard for whether or not a second UN resolution would be passed at the time – appear to further contradict a speech made by Tony Blair to the House of Commons on 23 February 2003, in which he said: "I detest his [Saddam's] regime. But even now he can save it by complying with the UN's demand. Even now, we are prepared to go the extra step to achieve disarmament peacefully."