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

Survivors and mourners of the attack brought a case at the Investigative Powers Tribunal (IPT) against the Security Services, arguing at a hearing earlier this month that the failure to take “adequate measures” to prevent the atrocity breached their human rights.

But in a ruling on Friday, Lord Justice Singh and Lady Justice Farbey said the cases could not go ahead because they were brought too late.

Lord Justice Singh said: “We are particularly mindful of the importance of the rights at issue… We are also mindful of the appalling impact of the atrocity on the applicants and their families.

“Any reasonable person would have sympathy for them.

“The pain and trauma they suffered, especially where young children were killed, is almost unimaginable.

“However, we have concluded that in all the circumstances it would not be fair to allow the applications to proceed.”

The judge said that while the tribunal “easily understands” why the legal claims were not brought until after the final report of the inquiry into the attack, “real expedition” was needed at that time.

Lord Justice Singh continued: “We have regard to the other matters that needed to be investigated and the arrangements that needed to be put in place, but in our view the drafting of the procedure was not given priority which, objectively assessed, should be put in place. they were.”

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

They continued: “Ever since the attack in May 2017, our customers have had to endure ongoing 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. “

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

Following the findings, the agency’s director general, Ken McCallum, expressed deep regret that such information had not been obtained.

Two reports of suicide bomber Salman Abedi were assessed at the time by the security service as unrelated to terrorism.

But inquiry chairman Sir John Saunders said after hearing from MI5 witnesses at hearings about the May 2017 atrocity, which killed 22 people and injured hundreds more, he believed it did not paint an “accurate picture”.

Lawyers for those affected previously said the investigation found there was a “real possibility” that one of the informants had obtained information that could have led to action to prevent the attack.

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