MPs are to quiz the Prime Minister over why Dewsbury suicide bomber Mohammed Sidique Khan was not investigated, despite being known to police.
The Intelligence and Security Committee has questioned why the July 7 bomber, who killed seven people with a suicide bomb in Edgware Road station, was not suspected of being a key player in a radical group despite being know to counter-terrorism officials.
Now Tony Blair is expected to face further questions over the security services.
The committee also expressed concerns about the quality of intelligence on the activities of British militants in Pakistan prior to the four suicide bombings on London's transport network.
It is also said to be critical of the system of alert and threat levels, which it ruled was unclear.
The national threat level was lowered from "severe, general" to "substantial" just before the attacks that killed 52 people and injured hundreds in the height of summer.
The committee said that although it was probably irrelevant to the bombers' plans, the warning system needed to be simplified for the public.
Khan, 30, who lived in Thornhill Lees, was one of the four bombers who took part in the attacks last summer by detonating explosives in a rucksack on his back.
Counter-terrorism officials were said to be aware of Khan, but he was not suspected of being a key player in a radical group.
The report, which will be handed to Tony Blair, was gathered from interviews with the police and intelligence community.
Khan led the suicide bombers, who also include 18-year-old Jermaine Lindsay who was brought up in Rawthorpe.
The others were Shehzhad Tanweer and Hasib Hussain, who both lived in Leeds.
The four targeted three Tube trains and a London bus.