The security service MI5 did not have the manpower to do extra checks on the 7 July ringleader before he carried out the attacks in 2005, a report has said.
But the Intelligence and Security Committee declined to criticise MI5, which it said had other priorities.
It stressed that while officers knew of Mohammad Sidique Khan's terrorist links, there was no evidence to suggest he was a threat to national security.
The Conservatives said there should be a judicial inquiry into MI5's actions.
Fifty-two people were killed in the suicide bombings in London in 2005.
The long-awaited report by a group of MPs describes in unprecedented detail what officers knew of Khan before the attacks.
It reveals that a police surveillance team filmed him in 2001 as part of an operation against suspected extremists.
However, he was not identified from the picture - and his significance was only realised after the bombings.

The report reveals that MI5 teams were stretched almost to breaking point in 2004 - the year before the attacks - attempting to trace terror suspects around the UK.
During that year, MI5 did not have the resources to watch 52 suspects who were classed as "essential targets".
In fact, the security service could only provide "reasonable" surveillance coverage of about one in 20 terror suspects - a fact the committee described as "astounding".
The committee said Khan and fellow 7/7 bomber Shehzad Tanweer were defined as "desirable" targets by MI5 after they were overheard discussing fraud and travel to Pakistan.
But resources were so stretched that officers could not even assess whether such "desirable" targets should be examined more closely unless they were known to be actively plotting an attack.
The committee's chairman, Kim Howells MP, said: "Hindsight is a wonderful thing. Those judgements were made at the time and, having gone in detail through all of the details, we cannot find any reason to criticise the actions that were taken at the time."
He said he hoped the report would put a stop to "speculation" and "conspiracy theories" which had caused distress to the families of the 7/7 victims.

There were six contacts recorded by MI5 and police with Khan between 1993, when he was arrested for assault, and January 2005, when a hire car was linked to a terror investigation.
Surveillance teams also witnessed several meetings between Khan and Tanweer and Omar Khyam, the man later discovered to be the leader of a plot to detonate fertiliser bombs.
Analysts decided the three men were not planning an attack and were instead involved in financial fraud.
   

This to me seems crazy..After reading this i think M15 made several key errors. And i think that if those errors had not been made the 7th of july bombings would not have happend.

Frenzy
My President is black, infact hes half white so even in a racist mind hes half right