Survivors of the July 7 London bombings has launched legal action over the government's refusal to set up a public inquiry.

The group applied for judicial review of a decision by the home office not to hold a full independent hearing.

But a home office spokesman said it had not been served with such legal papers, and it could therefore not comment.

Former Prime Minister Tony Blair ruled out such an inquiry in May.

However, he did ask Parliament's intelligence and security committee to review MI5's handling of intelligence about two of the July 7 bombers.

MI5 had watched the ringleader, Mohammed Sidique Khan, and his fellow suicide bomber Shehzad Tanweer while investigating another group of plotters.

Oury Clark Solicitors, which represents the survivors free of charge, said the group were "disappointed and saddened" by the government's decision.

"Their obviously preferred position was not to enter into litigation," said James Oury, of Oury Clark.

The "still-suffering" group decided to go ahead "so not to be further disadvantaged", he added.

"They recognise the wider public interest involved and the international importance of finding out the truth of events leading up to these bombings.

"They also feel an inquiry is a matter of essential public interest in order to improve the protection of all individuals whose lives remain at risk as a result of the ongoing threat of terrorism."

In the attacks of 2005, the four bombers blew up themselves on three Tube trains and a bus - killing 52 innocent people and injuring about 700.

Earlier this year, 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 bombers. They deny the charge and will stand trial next year.