AN EX-chief of staff of the Iraqi army has lost his bid to bring a private prosecution against Tony Blair over the war that devastated his country.

Last year the long-overdue Chilcot report revealed how Blair had made a personal pledge to then-US president George W Bush one year before the UK joined American-led military action to topple Saddam Hussein, promising: “I’ll be with you, whatever.”

Around half a million are estimated to have died between 2003 and 2011 as a result, according to an academic study published in 2013. The total includes fatalities from the invasion and insurgency as well as avoidable deaths caused by the collapse of infrastructure.

A total of 179 British military personnel also lost their lives.

General Abdul Wahed Shannan Al Rabbat accused Blair of committing a “crime of aggression” and sought to launch a private prosecution in the UK courts.

He also hoped to bring similar charges against two key ministers of the Blair government: former foreign secretary Jack Straw and ex-attorney general Lord Goldsmith.

Lawyers for the Oman-based accuser asked the High Court in London for permission to seek a judicial review in an attempt to get the Supreme Court to overturn a House of Lords ruling what the crime of aggression does not exist under the law of England and Wales.

But the application was dismissed yesterday when a panel of judges ruled there was “no prospect” of the case succeeding.

The case was brought after Westminster Magistrates Court last year refused to issue summonses on the grounds that the ex-ministers had immunity from legal action.

The current attorney general, Jeremy Wright MP, had also intervened in the case, calling the challenge “hopeless” and urging the High Court to block it.

Yesterday a spokesperson for his office said: “It should be for parliament, and not the courts, to create new criminal offences. This principle was upheld when the House of Lords ruled in 2006 that the ‘crime of aggression’ does not exist in English law.

“In this legal challenge, we argued that this remains the case today and the courts agreed.”

Representing Al Rabbat, who is based in Oman, Michael Mansfield QC had argued that the international crime of a war of aggression had been accepted by then-UK attorney general Hartley Shawcross in the 1940s, at the time of the Nuremberg trials.

He said the Chilcot report found Hussein had not posed an imminent threat to the UK, despite Blair’s claims, and now-discredited intelligence about weapons of mass destruction had been presented with “unwarranted certainty”.

The £10 million paper also concluded that peaceful alternatives to war had not been exhausted and the Iraq war had not been the “last resort” the Blair leadership had claimed.

Mansfield told the court the evidence was “emphatic”, stating: “It does not say there was an unlawful war or crime of aggression. It doesn’t need to, because the criteria are arguably all there.”

But, in their decision, judges Lord Thomas and Mr Justice Ouseley said the “clear principle” is that “it is for parliament and parliament alone” to decide on whether the crime or aggression should be assimilated into domestic law.

They said: “We see the force of Mr Mansfield’s contention that if there is a crime of aggression under international law, there should be a means of prosecuting it as otherwise the rule of law is undermined.”

In a two-hour defence of the decision to go to war made in response to the Chilcot findings last year, Blair said it was “the hardest, most momentous, most agonising” he had taken while in office.

Reaching out to affected families, he said: “I feel deeply and sincerely, in a way that no words can properly convey, the grief and suffering of those who lost ones they loved in Iraq, whether members of our armed forces, the armed forces of other nations, or Iraqis.”

He went on: “I will never agree that those who died or were injured made their sacrifice in vain."