The injured survivors of the Manchester Arena bombing are suing MI5, lawyers have said.

It comes after the security service’s chief last year acknowledged a “slim” chance of thwarting the attack was missed, with 22 people killed and hundreds injured in May 2017.

Three legal firms representing more than 250 people have since confirmed action has been submitted to the Investigatory Powers Tribunal (IPT), but provided no further details, saying it was an “ongoing legal matter”.

An inquiry found last March the bombing might have been prevented if MI5 had acted on intelligence received in the months before the attack.

Two pieces of information about bomber Salman Abedi had been assessed at the time by the security service to not relate to terrorism, according to the inquiry findings.

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As a result, MI5’s director general Ken McCallum made a rare public statement apologising for the failings identified and insisted improvements had been made.

“Having examined all the evidence, the chair of the inquiry has found that ‘there was a realistic possibility that actionable intelligence could have been obtained which might have led to actions preventing the attack’,” he said after the findings.

“I deeply regret that such intelligence was not obtained.

“Gathering covert intelligence is difficult – but had we managed to seize the slim chance we had, those impacted might not have experienced such appalling loss and trauma.

“I am profoundly sorry that MI5 did not prevent the attack.”

Read more:
Could MI5 have prevented Manchester bombing?
The security failings at Manchester Arena

Former national security adviser Sir Mark Lyall Grant previously told Sky News it was a “concern” intelligence was not acted upon, but that MI5 received “hundreds, if not thousands” of pieces a day.

“Mistakes can be made and things can slip through the cracks,” he added.

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Relatives of those who were killed in the attack have been critical of MI5, with the father of the youngest victim, Saffie-Rose Roussos, believing she would still be alive “if MI5 did their job”.

“Salman Abedi should have been stopped before he got to that arena and that’s MI5’s job,” Andrew Roussos previously told Sky News.

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Hudgell Solicitors, Slater & Gordon and Broudie Jackson Canter are the three firms leading the legal action at the IPT, which provides the right of redress to victims of unlawful action by a public body.

MI5 will not be commenting due to ongoing legal proceedings.

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