John Reid has rejected suggestions London bomber Mohammad Sidique Khan blamed his actions on the Iraq war.
Hundreds of bomb survivors are suffering from lasting injuries
The home secretary was asked if ministers wished to avoid a public inquiry because they feared it would fuel a debate about Iraq being a motive.
He said Iraq had not been mentioned in the bombers' wills or testaments.
In his testament Khan said: "Your democratically elected governments continuously perpetrate atrocities
against my people all over the world."
Mr Reid told the BBC: "If there had been any mention of Iraq from any of the bombers any where in the last will and testament of Khan in the Al Jazeera video which he made - that wouldn't have been hidden, couldn't have been hidden.
"The truth is it wasn't mentioned."
A September 2003 report by the cross-party Intelligence and Security Committee (ISC) revealed Tony Blair had been warned a month before war began that the threat from al-Qaeda and allied terrorist groups would be made worse by invading Iraq.
Mr Blair has acknowledged Iraq was being used to recruit terrorists but he has insisted it was not a valid excuse for terrorist atrocities.
Speaking shortly after the 7 July attacks the prime minister said: "Let us expose the obscenity of these people saying it is concern for Iraq that drives them to terrorism. If it is concern for Iraq then why are they driving a car bomb into the middle of a group of children and killing them?
"We are not going to deal with this problem, with the roots as deep as they are, until we confront these people at every single level - and not just their methods but their ideas."
On Thursday, the Home Office published a 'narrative' of the events leading up to the 7 July. A second report on the issue by the ISC was also published.
The Home Office report suggested the July bombers worked alone but Mr Reid has said there remained "considerable" circumstantial evidence of a link between them al-Qaeda, although he conceded there was no "direct verifiable" link.
Khan is believed to have visited Pakistan and possibly Afghanistan in 2003 and may have met al-Qaeda representatives.
And the attacker's video recorded prior to his death pays homage to the terrorist network.
Although Mr Reid cautioned: "It is quite possible for that organisation to claim any successful act of terrorism as that elevates them but there is considerable circumstantial evidence there."
Mr Reid has rejected calls for a public or independent inquiry into the 2005 attacks on London from the Lib Dems and Tories. He said such a probe will merely divert funds from the fight against future attacks.
In his posthumous video statement Khan said: "Our religion is Islam - obedience to the one true God, Allah, and following the footsteps of the final prophet and messenger Muhammad... This is how our ethical stances are dictated.
"Your democratically elected governments continuously perpetrate atrocities against my people all over the world.
"Until we feel security, you will be our targets. And until you stop the bombing, gassing, imprisonment and torture of my people we will not stop this fight."