A former counter-terror boss is expected to clear the security services of serious blunders over the Manchester Arena bomb but will call for an overhaul in how they spot terrorists.
David Anderson QC will today say an exhaustive review has concluded clear chances were not missed to stop Salman Abedi before he blew himself up in May.
But the report will confirm MI5 received information on the terrorist that could have been treated more seriously and turned him into a ‘high-priority’ target.
This would have meant he was put under surveillance and potentially prevented from murdering 22 innocent people.
![Khalid Masood killed five people in an attack in London](https://i.dailymail.co.uk/i/pix/2017/12/05/01/46FE294600000578-0-image-m-5_1512437748520.jpg)
Manchester Arena bomber Salman Abedi (left) and Westminster attacker Khalid Masood (right) were both on the radar of security services before they struck
![Security services are set to be cleared of any blame over the Manchester attack, but it is expected changes in how terrorists are spotted will be called for](https://i.dailymail.co.uk/i/pix/2017/12/05/01/46FE296B00000578-0-image-a-7_1512437761952.jpg)
Security services are set to be cleared of any blame over the Manchester attack, but it is expected changes in how terrorists are spotted will be called for
![Today's report is expected to confirm MI5 had received information on Abedi that could have been treated more seriously](https://i.dailymail.co.uk/i/pix/2017/12/05/01/46FE295D00000578-0-image-a-8_1512437778214.jpg)
Today’s report is expected to confirm MI5 had received information on Abedi that could have been treated more seriously
And he is expected to say Khalid Masood, who killed five people in an attack in Westminster in March, was also on the radar of the security services before he struck in March, reports the Sun.
Mr Anderson is set to make a series of recommendations that will improve how suspected terrorists are tracked in the future.
The proposals include setting up a new computer algorithm that could detect behavior indicating an involvement in terror.
The technology would be able to scour the list of 20,000 former ‘subjects of interests’ to see if they were re-engaging with terrorist activities.
The reviews were ordered by MI5 and the police following a spate of terror attacks on British soil in Westminster, Manchester, London Bridge, and Finsbury Park.
The assessments have been carried out internally but Mr Anderson was appointed by the Government to provide ‘independent assurance’.
![Five people were killed when Khalid Masood struck near Parliament. It was just one of several terror attacks on UK soil this year](https://i.dailymail.co.uk/i/pix/2017/12/05/01/46FE295000000578-0-image-a-9_1512437783845.jpg)
Five people were killed when Khalid Masood struck near Parliament. It was just one of several terror attacks on UK soil this year
![Counter-terror teams are running about 500 live investigations involving 3,000 individuals at any one time](https://i.dailymail.co.uk/i/pix/2017/12/05/01/46FE294B00000578-0-image-a-10_1512437787533.jpg)
Counter-terror teams are running about 500 live investigations involving 3,000 individuals at any one time
Mr Anderson, the former independent reviewer of terrorism legislation, submitted his classified report to the Home Secretary last month and a version of his findings will be made public today.
The Parsons Green attack in September is not covered by the report.
The events of 2017 have prompted questions for MI5 and the national counter-terror policing network.
Last month it emerged security services had been handed information on 22-year-old Abedi before he blew himself up on May 22, killing 22 innocent people.
![Former anti-terror chief David Anderson QC is expected to clear security services of major blunders](https://i.dailymail.co.uk/i/pix/2017/12/05/01/46FE292300000578-5145967-Former_anti_terror_chief_is_expected_to_clear_security_services_-a-12_1512438481980.jpg)
Former anti-terror chief David Anderson QC is expected to clear security services of major blunders
The tip-off was not considered to be highly significant at the time.
A source told the Sunday Times: ‘There were a few calls made regarding several bits of intelligence which, if judged differently at the time, would have turned Abedi into a high priority case.
‘And when a target is judged a high priority you should place them under surveillance.’
In a speech in October, the head of MI5 Andrew Parker said that when an attack happens ‘we are determined, using the harsh light of hindsight, to squeeze out every last drop of learning so that we can be the very best we can be, now and in the future.’
The scale of the current threat is seen as unprecedented.
Counter-terror teams are running about 500 live investigations involving 3,000 individuals at any one time, while there is also a wider pool of 20,000 former ‘subjects of interest’ who must be kept under review.
It is understood police and MI5 have foiled nine plots since the Westminster attack in March, in addition to the terrorist incidents that have occurred.