Victims of the July 7 bombings have taken the first step towards bringing legal action against the Government as they continued their fight for an independent public inquiry into the terrorist attacks.
Bereaved relatives and survivors of the 2005 atrocity delivered a pre-action protocol letter to the Home Office, renewing their calls for an investigation but warning no action would result in a legal challenge.
In May, former Prime Minister Tony Blair ruled out demands for a new inquiry into the attacks but did order the Intelligence and Security Committee (ISC) to review MI5's handling of intelligence about two of the July 7 bombers.
The decision came after it emerged MI5 had observed July 7 ringleader Mohammed Sidique Khan and sidekick Shehzad Tanweer while investigating another group of plotters.
The latest legal document is a formal move necessary before judicial review proceedings can be issued at the High Court.
Lawyer James Oury, senior partner of Oury Clark Solicitors which represents the victims involved with the presentation, said: "There is continued uncertainty over the events leading up to the attacks on July 7, 2005 and an independent inquiry is seen as an appropriate way to address this concern.
"Our clients have endured unimaginable suffering in physical and emotional terms and it is unfair and inappropriate for the Government to force our clients into an adversarial, costly and complex court setting - a litigation corner."
Earlier this month, three men - Mohammed Shakil, 30, Sadeer Saleem, 26, and Waheed Ali, 23, from Beeston, Leeds - became the first people to appear in court charged with conspiring with the July 7 bombers. They deny the charge and will stand trial next year.
A Home Office spokeswoman said: "The Government understands the feelings of the survivors and relatives of those killed in the 7 July bombings. That is why the independent Intelligence and Security Committee has been asked to carry out further inquiries to reappraise their findings in light of all the evidence and we will study the ISC's findings carefully.
"However, as we have consistently maintained, experience has shown that a fuller public inquiry can (like the Saville inquiry) take years and divert huge resources in terms of those who would be required to give evidence - in this case the police and security service who are already stretched greatly countering the terrorist threat."