GORDON Brown has said that George W Bush’s administration deliberately “misled” the UK about weapons of mass destruction (WMD) before the Iraq war.

Brown claims the US defence department knew Saddam Hussein did not have the weapons. However, that knowledge was withheld from the UK government when seeking its backing for the Iraqi invasion, Brown said.

The former Prime Minister makes the dramatic revelations in his new book My Life, Our Times, which is published on Tuesday.

Last night, the mother of a Scottish soldier killed in Iraq dismissed Brown’s claim he was unaware WMDs did not exist in 2003. Rose Gentle’s 19-year-old son Gordon was killed by a roadside bomb while serving in Basra in 2004. She said: “He [Brown] helped fund the war so he must have known.”

SNP MP Chris Stephens, meanwhile, accused Brown of failing to take responsibility for a decision taken by a government he was a senior member of.

In his new book, Brown said that a secret US intelligence report commissioned by Bush’s defence secretary Donald Rumsfeld into WMD was not passed to UK ministers.

In extracts from his book, Brown’s suggests that sight of it by UK ministers could have prevented the war in 2003.

At the time of the conflict, Sunday Herald reporters, including now editor Neil Mackay, spoke to intelligence experts and diplomats all of whom did not believe the UK government’s assertions.

Mackay was an investigative reporter for the paper in 2003. The Sunday Herald later published his book, The War on Truth, about the spin that led to war. Mackay said later: “In the run-up to the invasion of Iraq our paper ran story after story on the phoney case for war. We spoke to diplomats, we spoke to spies and we spoke to weapons inspectors.

“None of them thought Iraq had weapons of mass destruction. Many of them thought a war would bring more terror to Iraq and to the West. Blair was telling us lies and he still is today.”

However, Brown now claims UK and US inquiries into the Iraq war had not seen the Rumsfeld dossier. He said he only became aware of the existence of the report after he left government in 2010. Brown is understood to have been leaked the paper in the years after he left office.

“In these months before the war, I had no idea that key decision makers in America were already aware that the evidence on the existence of WMDs was weak, even negligible and in key areas non existent,” Brown said.

He added: “Having reviewed all of the information now available – not just that revealed by the Hutton, Butler and Chilcot inquiries but in America too – I feel I now understand how we were all misled on the existence of WMDs.”

In 2010, shortly before he left office, Brown, said Tony Blair’s decision to go to war in Iraq was “the right decision for the right reasons”.

However, in his book Brown talks about the “rush to war”. Brown also reflects on whether he could have done more to raise doubts in Blair’s cabinet about supporting the US-led led invasion.

He said that as Chancellor at the time of the conflict he was kept in the dark about intelligence information.

Brown said: “When I consider the rush to war in March, 2003 – especially in light of what we now know about the absence of weapons of mass destruction – I ask myself over and over whether I could have made more of a difference before that fateful decision was taken.

“Chancellors have seldom been at the centre of decision-making in matters of war and peace. My official role leading up to the conflict was to find the funds for it. At the time, therefore, I had as much and as little access to security and intelligence information as most other cabinet ministers.”

However, Brown says that he was initially shown convincing evidence by top intelligence officials about the existence of WMDs.

He said: “I was told they knew where the weapons were housed. I remember thinking at the time that it was almost as if they could give me the street name and number where they were located.”

Brown highlighted papers held by the US defence department and based on work by their intelligence service, which was commissioned by Rumsfeld.

He said: “We now know from classified American documents, that in the first days of September 2002, a report prepared by the US Joint Chief of Staff’s director for intelligence landed on the desk of the US Defence Secretary, Donald Rumsfeld. ‘Please take a look at this material as to what we don’t know about WMD’, Rumsfeld then wrote to Air Force General Richard Myers. ‘It is big’, he added.

“So it was. Commissioned by Rumsfeld to identify gaps in the US intelligence picture, it is now clear how forcibly this report challenged the official view: ‘We’ve struggled to estimate the unknowns . . . We range from 0 per cent to about 75 per cent knowledge on various aspects of their [Iraq’s WMD] program’, the report stated.

“It conceded that US knowledge of the Iraqi nuclear weapons programme was based largely – perhaps 90 per cent of it – on analysis of imprecise intelligence.

“These assessments, the report said, relied ‘heavily on analytic assumptions and judgment rather than hard evidence. The evidentiary base is particularly sparse for Iraqi nuclear programs.”

“And as for missiles and the Iraqis’ ability to target countries such as the UK with them, which was to be the subject of dramatic claims only a few weeks later, Rumsfeld was informed: ‘We doubt all processes are in place to produce longer-range missiles.”

Brown said that “this highly-confidential US evidence was a refutation not only of the claim that Iraq was producing WMDs but also of their current capability to do so.”

“It is astonishing that none of us in the British government ever saw this American report,” Brown says.

However, Brown claimed it is not clear who in George W Bush’s White House saw the intelligence report commissioned by Rumsfeld.

He said: “Because there has been no Chilcot-style inquiry in the USA, we do not know to this day who in the US administration saw the Rumsfeld dossiers.”

Brown also said that he had begun planning the UK’s eventual withdrawal from Iraq in early 2009 when he became Prime Minister in June 2007.

Rose Gentle’s son Gordon was killed in Basra in 2004. She said: “He [Brown] helped fund the war so he must have known. I take what he’s saying with a real pinch of salt. He could have come forward with this information before now even if he didn’t find out until he left power. I’m disappointed as he should have spoken up before now.”

SNP MP Chris Stephens was critical of Brown for failing to take responsibility for a decision taken when he was a senior member of the government.

The Glasgow South West MP said: “These comments from Gordon Brown echo those made in the autobiography of Ed Balls that the Treasury was solely focused on finding the money for the war. It beggars belief that the Treasury focus at that time was not on the policy and human implications of the biggest foreign policy disaster in decades unfolding under their noses.”

Neil Mackay is not editing the Sunday Herald this week.