More than 300 people affected by the Manchester Arena bombing cannot continue their legal action against MI5, judges at a specialist tribunal have ruled.

Survivors and people bereaved by the attack brought a case to the Investigatory Powers Tribunal (IPT) against the Security Services, claiming at a hearing earlier this month that the failure to take “appropriate measures” to prevent the atrocity infringed their human rights.

But in a ruling on Friday, Lord Justice Singh and Mrs Justice Farbey said the cases could not proceed as they were brought too late.

Lord Justice Singh said: “We are particularly conscious of the importance of the rights concerned… We are also conscious of the horrendous impact of the atrocity on the claimants and their families.

Tributes left after the suicide bombing at the Manchester Arena
The tragedy claimed the lives of 22 people (PA)

“Any reasonable person would have sympathy for them.

“The grief and trauma which they have suffered, particularly where young children were killed, is almost unimaginable.

“Nevertheless, we have reached the conclusion that, in all the circumstances, it would not be equitable to permit the claims to proceed.”

The judge said that while the tribunal “readily understand” why the legal claims were not filed until after the final report from the inquiry into the attack, “real expedition” was needed at that point.

Lord Justice Singh continued: “We bear in mind the other matters that had to be investigated and arrangements which had to be put in place but, in our view, the filing of the proceedings was not given the priority which, assessed objectively, it should have been.”

He also said that if the claims had gone ahead, the security services would have needed to “divert time and resources to defending these proceedings rather than their core responsibilities”.

“Those responsibilities of course include the protection of the lives of people in this country by, for example, preventing future attacks,” Lord Justice Singh added.

Hudgell Solicitors, Slater & Gordon and Broudie Jackson Canter, three of the law firms representing people affected, described the ruling as “extremely disappointing for our clients”.

Manchester Arena Inquiry
MI5 director-general Ken McCallum expressed regret after the inquiry into the bombing (Danny Lawson/PA)

They continued: “Ever since the attack in May 2017, our clients have had to endure continued delays but have done so with great patience and understanding in the hope that by allowing all legal processes to be fully explored, transparency and justice would be achieved.”

The inquiry into the bombing found it might have been prevented if MI5 had acted on key intelligence received in the months before the attack.

In the wake of the findings, the agency’s director-general, Ken McCallum, expressed deep regret that such intelligence was not obtained.

Two pieces of information about suicide bomber Salman Abedi were assessed at the time by the security service to not relate to terrorism.

But inquiry chairman Sir John Saunders said, having heard from MI5 witnesses at the hearings into the May 2017 atrocity which killed 22 people and injured hundreds of others, he considered that did not present an “accurate picture”.

Lawyers for those affected previously said the inquiry found there was a “real possibility” that one of the pieces of intelligence could have obtained information which may have led to actions preventing the attack.

And at the hearing earlier this month, Pete Weatherby KC, for those affected, described the IPT claims as “the next step” in vindication for his clients after the inquiry’s findings.

The tribunal heard that the cases on behalf of survivors, those who died and people who were affected by proximity to the aftermath were due to be led by three lead cases.

These are the cases of Chloe Rutherford, 17, from South Shields, who died in the attack, Eve Hibbert, who suffered severe brain damage, and Lesley Callander, whose 18-year-old daughter Georgina was killed.