Filmed in 2004: Suicide bombers and bomb plotter Enlarge Image

On Monday it emerged at the end of a year-long terror trial that MI5 had two of the 7 July plotters under surveillance a year before the attacks.

But Home Secretary John Reid ruled out an inquiry into MI5's failures.

A letter to Mr Reid calling for an inquiry will be delivered later by members of the 7/7 Inquiry Group.

When and where plotters met 7 July bombers

On Monday five men were given life sentences for a foiled plot to build a huge fertiliser bomb for a UK attack.

It emerged during the trial that MI5 had tailed London suicide bombers Mohammad Sidique Khan and Shehzad Tanweer while investigating that case, but took no action.

Rachel North, who survived the blast o­n the Piccadilly Line train in 2005, said she was shocked and appalled when she learned that Khan and Tanweer were not the "clean skins" she had believed.

'On the radar'

She said: "Now that we have discovered these men were very much o­n the radar of the security service and could have been stopped, that is going to be very difficult to come to terms with.

"This has fuelled my desire for an independent inquiry because it appears we have not been told the truth about what happened and what we knew about these bombers prior to 7/7."

EVIDENCE SINCE TRIAL Khan followed Feb 2004 Photographed with extremists Recorded talking with plot ringleader Home address seen Car ownership and surname known June 04

But Paul Dadge, who also survived the London bombings, said it was easy to be critical with hindsight.

He said he believed the attacks may have been prevented if the leads had been followed but argued that it was important to praise the security services for successfully securing convictions.

Mr Reid has rejected the need for an inquiry and said it would divert too many MI5 officers from the job of foiling other terrorist plots.

But he has asked the Intelligence and Security Committee (ISC) to consider why the 7 July bombers were not picked up.

The committee, which comprises MPs and Lords, is expected to examine claims that West Yorkshire Police special branch was not told about the MI5 surveillance operation.

ISC chairman Paul Murphy MP has indicated that police were informed.

'Divert energy'

Tony Blair has also rejected calls for a public inquiry, although he said he "totally" understood why some people sought o­ne.

The row has taken the shine off the conviction of the five men

He told GMTV: "The problem if you have an independent public inquiry into something like this is you will divert all their energy and attention into trying to answer the questions that come up in the inquiry."

Former home secretary David Blunkett said there was no need for a public inquiry "because it is lengthy, expensive and it presumes that we don't have the facts, and we do".

He told BBC Radio 4's Today programme: "It would be a great boon for the terrorists, and those associated with them, to see us to trawl the exact detail of everything that went o­n."

These comments follow suggestions that the 7 July attacks could have been avoided.

'Clean skins'

"We shouldn't lose sight of the five who were locked up," he said, adding that it is "a shame" that the success of security services had been overlooked."

One critical issue is what MI5 told both the public and politicians in the wake of the 7 July attacks.

The media were briefed that Khan and fellow bombers were "clean skins" - men with no previous record of terrorist associations. Evidence following the end of the trial reveals MI5 photographed Khan as he met other extremists, followed him home - and by the summer of 2004 they knew his surname and that he owned a car.

WHAT MI5 TOLD COMMITTEE We have been told in evidence that none of the ... 7 July group had been identified (that is named and listed) as potential terrorist threats prior to July ISC report into MI5, 2006

The revelation that o­ne of the 7 July bombers met up with o­ne of the fertiliser bomb plotters - Omar Khyam - at a terrorist training camp in Pakistan has caused concern.

However, the head of Pakistan's National Crisis Management Centre, Brigadier Javed Iqbal Cheema, said anyone "who spends a lot of money and travels to Pakistan...[is] already motivated for a particular reason".

Meanwhile, Liberal Democrat leader Sir Menzies Campbell responded to details that emerged in bomb plot trial by saying it would "spark widespread public concern and debate about the operational capabilities of the security service, and the reliability of government information in the aftermath of the 7 July bombings".

And Shadow Home Secretary David Davis said: "Whether deliberately or not, the government have not told the British public the whole truth about the circumstances and mistakes leading up to the July 7 attacks."