More than 250 survivors of the 2017 Manchester Arena bombing are reportedly taking legal action against MI5 for not preventing the attack.
The explosion after the Ariana Grande concert killed 23 people, including the Islamic extremist suicide bomber Salman Abedi, and injured 1,017.
The BBC reported on Sunday that legal teams representing survivors have submitted a group claim to the Investigatory Powers Tribunal.
Hudgell Solicitors, Slater & Gordon and Broudie Jackson Canter are all reported to be legal firms involved in the case.
A statement on behalf of Hudgell Solicitors, Slater and Gordon, and Broudie Jackson Canter, said: “Legal teams representing injured survivors of the Manchester Arena bombing in 2017 can confirm that they have collectively submitted a group claim on behalf of more than 250 clients to the investigatory powers tribunal (IPT).
“As it is an ongoing legal matter, we are unable or provide any further details, or comment further, at this stage.”
MI5 has said it will not comment on active cases has previously apologised to victims for not preventing the attack.
Last year MI5 director-general Ken McCallum shared regrets that linked Abedi to explosives was not followed up upon.
"Gathering covert intelligence is difficult," Mr McCallum said, "but had we managed to seize the slim chance we had, those impacted might not have experienced such appalling loss and trauma."
He added: “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.
"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."
An inquiry last year found that MI5 missed a “significant opportunity” to prevent the attack.
