"As a result of the failings, potential opportunities to prevent it were missed."

Counter-terrorism police and the MI5 missed crucial chances to prevent the devastating 2017 Manchester Arena attack, a parliamentary watchdog has concluded.

Salman Abedi detonated a homemade suicide bomb in the foyer of Manchester Arena in May 2017 as fans left an Ariana Grande concert, killing 22 people and injuring more than 100 others.

In a new report on the five terrorist attacks that occurred in England in 2017, the handling of Abedi’s case by MI5 and counter-terror cops was singled out for criticism.

Dominic Grieve, the chair of the intelligence and security committee (ISC), 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 on 22 May, we have concluded that, as a result of the failings, potential opportunities to prevent it were missed.”

Specifically, the report reveals that both the M15 and counter-terrorism police failed to act after Abedi visited a known extremist in prison. The extremist was previously jailed for helping young men travel to Syria to fight alongside ISIS militants. It was also revealed that he faced no travel restrictions, which meant that he had been allowed to return to the UK from a suspected trip to Syria only four days before the attack.

Although Abedi was considered to be of interest to MI5, he was at no point under active investigation after security services “moved too slow” in investigating him before the attack.

There was also criticism for the Parsons Green bomb attack in September 2017 – when a bomb failed to fully detonate on a London Overground train.

Grieve added: “This is unacceptable. From what we have seen to date, there were fundamental failings in the handling of this case by the Home Office, the police and Surrey county council.

“This litany of errors will require a separate comprehensive review to which the Home Office must be directly answerable.”