Allegations that British troops killed and tortured Iraqi civilians a decade ago were the product of a conspiracy to pervert the course of justice and get compensation payments, a public inquiry has heard.
In closing statements to the long-running Al-Sweady Inquiry, lawyers for British soldiers and the Ministry of Defence said claims that UK troops killed Iraqis after the Battle of Danny Boy in May 2004 were a "criminal conspiracy" to mislead previous high court proceedings and commit perjury at the inquiry.
They accused Iraqis who made the allegations of trying to deceive the inquiry into believing detainees had been mistreated for an "ulterior motive" of financial compensation, causing "immense anxiety and distress" to soldiers, and a cost of more than £22 million to the public purse.
The inquiry was set up to examine allegations that 20 or more Iraqis were unlawfully killed at Camp Abu Naji (CAN) near Majar-al-Kabir, southern Iraq on May 14 and 15 2004; that dead bodies were mutilated by British soldiers; and that detainees were ill-treated at CAN and later at another base.
It was ordered in 2009 amid concerns by High Court judges that the MoD had not properly investigated the events of May 2004.
The inquiry, whose cost stands at £22,695,939, started oral hearings last year and has heard evidence from nearly 300 witnesses.
In an unexpected move last month, claims that British soldiers murdered Iraqi civilians were dropped after lawyers representing the alleged victims' families admitted there was no evidence it happened.
Inquiry chairman Sir Thayne Forbes will continue to examine allegations of mistreatment of Iraqi detainees after the battle, with his report expected by the end of this year.
In closing statements today, lawyers for the MoD and for British soldiers involved in the inquiry branded the allegations the result of a "conspiracy" by its Iraqi core participants.
The MoD said: "The untruthful allegations cannot be attributed to honest mistakes or misunderstandings.
"They are the product of a conspiracy between a number of the Iraqi core participants to pervert the course of justice.
"The conspiracy has resulted in immense anxiety and distress to a number of brave servicemen and a cost to British taxpayers of well in excess of £20 million."
The MoD dismissed several other allegations - including claims that British soldiers used "microbial weapons" - as "patently untrue", but did admit there had been some instances where the conduct of British soldiers fell below expected standards.
Jeremy Johnson QC, for the MoD, told the inquiry that the only "cover-up" had been perpetrated by Iraqi core participants.
He said the inquiry had revealed: "a criminal conspiracy to make false allegations of murder and to mislead the administrative court and to commit perjury in this room".
Neil Garnham QC, representing the majority of British soldiers involved in the inquiry, said there had been a "deliberate and co-ordinated" attempt to give misleading evidence.
He said: "They have actively participated in attempts to deceive the courts and this inquiry into believing that Iraqis were tortured and killed at CAN."
He added: "They were also witnesses, who in addition to having a clear ulterior motive to make allegations of mistreatment in the form of claims for financial compensation, have expressed a violent antipathy towards the coalition forces and those they consider responsible for their detention."
The inquiry heard that a document had eventually emerged showing that the men who lost their lives were members of the insurgency, and the accounts of some Iraqi witnesses for why they were on the battlefield were today described as "riddled with inconsistencies" and "elaborate fabrication".
Mr Garnham said: "If the inquiry concludes, contrary to their accounts, they were involved in the ambush, then they have all repeatedly, persistently and deliberately given false evidence, including on oath, to you sir."
He said accounts of alleged abuse at CAN were "implausible, confused and internally inconsistent", with some detainees having "exaggerated and fabricated" accounts of ill-treatment.
But Patrick O'Connor, QC, from Public Interest Lawyers - representing the Iraqi claimants - said although allegations of unlawful killing had been dropped, claims of mistreatment were "grave".
He said: "None of this would have been necessary if they (the MoD) had acted responsibly and in the public interest years ago.
"The heavy cost of this inquiry is the heavy cost of their dereliction of legal, moral and professional duty."
Of allegations of mistreatment, he said: "These issues are grave indeed: gross violations of the Geneva Conventions, inhuman and degrading treatment of wounded, broken and helpless young men, who were utterly at the mercy of their military handlers and interrogators."
He added: "It would be a tidy landscape if our armed forces were safe from accountability to the rule of law.
"Some may describe that as Arcadian. Some others may describe it perhaps as Orwellian. Sir, we are witnesses to the cold arrogance of the British state at work."
The closing statements mark the end of hearings for the inquiry, which is expected to publish its report in November.