TEHRAN (Press Shia) – Former British Prime Minister Gordon Brown said that crucial US intelligence that cast doubt on claims of Iraq's weapons capabilities was not shared with Britain in the lead up to war in 2003.

Brown, who served as Chancellor of the Exchequer at the time of the 2003 military intervention, revealed that the US had failed to share intelligence that seriously challenged the notion that Iraq had weapons of mass destruction (WMDs), UK based Telegraph Daily reported.

He noted that this information only became available to him after he resigned as prime minister in 2010.

"We now know from classified American documents, that in the first days of September 2002 a report prepared by the US Joint Chiefs of Staff's director for intelligence landed on the desk of the US defense secretary, Donald Rumsfeld," Brown said. "Commissioned by Rumsfeld to identify gaps in the US intelligence picture, it is now clear how forcibly this report challenged the official view".

"If I am right that somewhere within the American system the truth about Iraq's lack of weapons was known, then we were not just misinformed but misled on the critical issue of WMDs. Given that Iraq had no usable chemical, biological or nuclear weapons that it could deploy and was not about to attack the coalition, then two tests of a just war were not met: war could not be justified as a last resort and invasion cannot now be seen as a proportionate response," he added.

Britain joined the US, led by then-president George W. Bush, in invading Iraq following allegations that Saddam Hussein was storing WMDs.

The UK government compiled two dossiers, one of which was dubbed the 'Dodgy Dossier' by the British press, in which military action in Iraq was justified to the public.

Among the claims made about Iraq's Ba'athist regime was that it could deploy biological weapons within 45 minutes of an order.

The intelligence seen by Brown after his resignation suggests that as much as 90 percent of the intelligence on Iraq's weapons capabilities relied on assumptions.

Brown admits this in his in latest book My Life, Our Times, which is due for release next week.

"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," the former prime minister recounts.

"It is astonishing that none of us in the British government ever saw this American report."

The former chancellor and premier's revelations concur with the findings of the Chilcot Report, which after seven years of investigation concluded that Saddam posed "no imminent threat" in 2003 and that the war justified on "flawed" evidence.

Brown says that in his role as chancellor at the time, his only involvement was to find funds for the military intervention.