(BBC) MI5’s failure to prevent the Manchester Arena attack centred on a mistake so serious that it could be seen as negligent, the BBC has been told.
The security agency apologised in March for not preventing the suicide bombing by Salman Abedi, who killed 22 people.
Two sources told the BBC that MI5 received intelligence in the months before the 2017 attack, linking Abedi to a possible bomb plot.
The government said it would “not confirm or deny allegations.”
But the well-placed sources anonymously told us that the information was assessed as unreliable.
