Former minister Michael Meacher has blamed the Iraq war on the US desire for world domination.
The remarks come as more UK troops are deployed to Iraq
Mr Meacher also suggested the Americans might have failed to prevent 11 September as it gave a pretext for military action.
His comments come as Britain prepares to send more troops to Iraq to cope with the deteriorating security situation.
Mr Meacher was environment minister until three months ago and has already spoken out in opposition to the war, describing the case for it as an "uncertain fantasy".
Writing in the Guardian newspaper, Mr Meacher said the 11 September attacks gave an invaluable excuse for attacking Afghanistan.
And he said the US Government intended to take military control of the Gulf region whether or not Saddam Hussein was in power because of its need for further secure oil supplies.
Mr Meacher also criticised the British Government for what he called its collusion with the US and its own scramble for oil.
Downing Street said the government did not share his views comments.
"He is obviously no longer a member of the government. His views are obviously not ones that the prime minister would share," said a spokesman.
Earlier, another spokesman for Tony Blair pointed out that profits from Iraqi oil were being put in a trust fund for the country's reconstruction.
In his piece Mr Meacher wrote: "It seems that the so-called war on terrorism is being used largely as a bogus cover for achieving wider US strategic geopolitical objectives.
"The evidence again is quite clear that plans for military action against Afghanistan and Iraq were in hand well before 11 September.
"The global war on terrorism has all the hallmarks of a political myth propagated to pave the way for a wholly different agenda - the US goal of world hegemony, built around securing by force command over the oil supplies required to drive the whole project."
Speaking on BBC Radio 4's Today programme, he said this agenda had been outlined by the Project for the New American Century (PNAC) - a thinktank associated with leading neoconservative hawks within the US administration.
Challenged to explain the presence of prominent non-neoconservatives within the administration such as Secretary of State Colin Powell, he said:
"I think you need to look at the broad stretch of US policy and decide what determines it. I would say to a great degree that it is not Colin Powell but fits very closely with the [PNAC]."
'No attempt' to catch Bin Laden
In his article, Mr Meacher also said the US had passed up opportunities to catch Osama Bin Laden and other senior al-Qaeda figures.
"No serious attempt has ever been made to catch Bin Laden," he claimed.
Mr Meacher told the Today programme he was not a conspiracy theorist and said he was simply "in favour of giving people the facts".
A spokesman for the US embassy told the Guardian Mr Meacher's views were ridiculous.
"His fantastic allegations - especially his assertion that the US government knowingly stood by while terrorists killed some 3,000 innocents in New York, Pennsylvania and Virginia - would be monstrous, and monstrously offensive, if they came from someone serious or credible."