Survivors of the July 7 bombings demanded a public inquiry into the attacks last night after a jury failed to reach verdicts on three British Muslims accused of carrying out a reconnaissance mission to London.

Waheed Ali, Sadeer Saleem and Mohammed Shakil visited the London Eye, the Natural History Museum and the London Aquarium while allegedly pinpointing potential targets seven months before the 2005 atrocity.

A jury at Kingston Crown Court failed to reach a verdict yesterday after 15 days of deliberation and a four-month trial that cost an estimated £10 million. The Crown Prosecution Service will decide next week whether there should be a retrial.

Lawyers representing survivors and relatives of victims said the trial had revealed significant details about how much the police and M15 knew about the bombers before the attacks.

The release of an updated report by the Parliamentary Intelligence and Security Committee is expected to be delayed until the end of any retrial. It is expected to be critical of the failure to identify the 7/7 ringleader Mohammad Sidique Khan as a serious terror risk.

Mr Justice Gross said yesterday: “I will work from the assumption that there might be a retrial and I will assume that it is likely to be in the new year.” The court set a provisional date for a directions hearing on September 26 or 29. The three men were remanded in custody.

Khan, 30, Shezhad Tanweer, 22, Hasib Hussain, 18, and Jermaine Lindsay, 19, detonated explosives on three Tube trains and a bus, killing 52 people and injuring almost 1000.

The court heard that Mr Ali, 25, Mr Saleem, 28, and Mr Shakil, 32, had denied conspiring with the bombers and others to cause explosions between November 17, 2004, and July 8, 2005.

All three admitted travelling to the capital with the bombers Hussain and Lindsay in December 2004 but insisted it was a social visit and not a “hostile reconnaissance”. The locations they had visited bore a “striking similarity” to where the bombs had been detonated, the court heard.

The defendants, of Beeston, Leeds, denied knowing about the attack and said that it was against their religion.

They admitted to being committed Islamic jihadists who had attended Pakistani terrorist training camps and were friends with the bombers.

Mr Ali had travelled to Pakistan with Khan in 2001 when Khan had fought on the Taleban frontline. He had also been present when Khan had made a farewell video for his daughter before allegedly preparing to fight British and American troops in Afghanistan in December 2004. Mr Ali said that killing a soldier was justified to “liberate the Muslim brothers from foreign occupiers”, but “you can’t kill innocent people. You can’t commit suicide. That is a bedrock of Islam.”

He had also been present when Khan and Tanweer had met a “committed terrorist” known as Ausman in Crawley, West Sussex, the court heard. Police and M15 had monitored the visits and bugged conversations in which the men discussed fighting jihad abroad and carrying out fraud.

Mr Saleem and Mr Ali had flown to Pakistan in December 2004 to meet Khan and Tanweer at a jihad training camp where the London plot was allegedly developed. However, the men insisted they had not met the bombers there and had not known of the plan.

Survivors of the bombings attended the trial and watched videos, shown in public for the first time, of the moment when two of the devices had exploded. Jacqui Putnam, who survived the Edgware Road bombing, said: “Our biggest concern is that the inquests will now be postponed and also the \ report.

“It is much worse for the bereaved because they need to have an inquest. They need to know and it’s still hanging over them. And because it is still hanging over them it is still hanging over us \ because we are all in this together.”

Robert Webb, whose sister Laura, 19, died at Edgware Road said that his family was “obviously disappointed”.

But he added: “We’d much rather be in this position than see a jury return an incorrect verdict. We don’t want to see innocent people jailed or guilty people go free.”

Solicitors acting for survivors and relatives said that the trial had provided more evidence of failures by the police and security service to prevent the London bombings. James Oury and Clifford Tibber, of Oury Clark solicitors, said the trial had shown that officials had known more about the bombings than they had made public.

The lawyers have sought a judicial review of the Government’s repeated refusal to hold a public inquiry.

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