Lawyers from three firms said on Sunday that more than 250 survivors of the suicide bombing that killed 22 people at a 2017 Ariana Grande concert in Manchester, England, are filing a lawsuit against Britain's domestic intelligence agency. 

An official investigation in March 2023 reported that the attack would have been prevented if Britain's MI5 security service had acted upon critical intelligence. 

Salman Abedi, a 22-year-old Manchester native of Libyan descent, carried out the suicide bombing as concertgoers were leaving the Manchester Arena in northern England.

According to the inquiry's findings, two pieces of information about Abedi at the time had nothing to do with terrorism. 

MI5's director general, Ken McCallum, issued a rare public apology, acknowledging the shortcomings discovered and stating that improvements had been accomplished.

McCallum said that after the findings, the chair of the inquiry had found a realistic possibility that actionable intelligence could have been obtained, which might have led to actions preventing the attack.

He said he deeply regrets that such intelligence was not obtained.

Furthermore, he claimed that gathering covert intelligence is difficult. However, he noted that if they had managed to seize the slim chance they had, those impacted might not have experienced such appalling loss and trauma. 

Former national security adviser Sir Mark Lyall Grant told Sky News that it was a concern that intelligence was not acted upon while MI5 received "hundreds if not thousands" of pieces daily. 

He added that mistakes can be made, and things can slip through the cracks. 

Relatives of those who lost their lives 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. 

Andrew Roussos told Sky News that Abedi should have been stopped before he got to that arena and noted that it is MI5's job.