A number of shortcomings in the handling of Salman Abedi before he launched a suicide attack at a pop concert in May last year, killing 22 people, were detailed by Parliament’s intelligence and security committee (ISC).
Abedi, 22, first came to the attention of MI5 in December 2010 and was briefly investigated by the agency in 2014.
The ISC assessment said:
l Abedi visited an extremist contact in prison on more than one occasion, but no follow-up action was taken by either MI5 or police;
l MI5 decided not to place travel monitoring or restrictions on Abedi, meaning he was allowed to return undetected to the UK in the days before he carried out the attack;
l MI5 systems moved too slowly after Abedi’s case had been flagged for review;
l Abedi was not at any point considered for a referral to the Prevent anti-terror scheme.
ISC chairman Dominic Grieve said: “What we can say is that there were a number of failures in the handling of Salman Abedi’s case and, while it is impossible to say whether these would have prevented the devastating attack, we have concluded that, as a result of the failings, potential opportunities to prevent it were missed.”
Mr Grieve said it was “striking” how many of the issues which arose in relation to the attacks last year had previously been raised by the committee in its reports on the 7/7 attacks and the killing of Lee Rigby.
The Conservative MP said: “We have previously made recommendations in all of these areas, yet the government failed to act on them.”
He noted that both MI5 and counter-terror police have been “thorough in their desire to learn from past mistakes”, adding: “The lessons from last year’s tragic events must now result in real action.”
The ISC, which has access to top-level security officials and classified material, reviewed the five attacks that hit Britain last year.
In total 36 innocent people were killed. In addition to the Manchester fatalities, five victims died in the Westminster attack in March, eight at London Bridge in June, and one at Finsbury Park in the same month.
Then in September, a bomb partially exploded on a Tube train at Parsons Green, injuring 51 people.
Prior to his attack, Abedi had travelled to Libya.