Interior minister Amber Rudd declined to comment on exactly what was known about Abedi when asked in several interviews on Monday. "He was not on any sort of Prevent agenda".
Counter-terrorism squads are trying to re-create Salman Abedi's movements in the days before he detonated a bomb at an Ariana Grande concert in Manchester, killing 22 people. The Guardian understands that Britain's domestic security service started one review last week, which aims to quickly identify any obvious errors, while the other will be more in depth.
The security service will examine assumptions that were made about Abedi before the attack, and has launched a "post-incident investigation" into how the bomber was overlooked, the BBC said.
"Obviously I am not privy to what the security service did or didn't know about that individual at this time, but from a police perspective that's what I knew", said Hopkins. But Chief Constable Ian Hopkins said Abedi had not been known to the government's counter-radicalization program known as Prevent.
USA officials, cited by NBC News, also reportedly said Abedi's family had warned security services that he was unsafe following his visit to Libya, while local community leaders in Manchester have told British broadcasters that two people close to Abedi had warned police that he had made comments supporting terrorism and had said that "being a suicide bomber was OK".
Officials also said extra police staffing that had been added to protect public gatherings over the holiday weekend would be reduced.
The railway station next to Manchester Arena, which had been shut since the blast, reopened Tuesday.More news: Comic says she 'went too far' with severed head video mocking Trump
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The May 18-22 timeline is crucial, because it's known that Abedi returned from Libya just a few days before the bombing.
More than 1,000 officers are working on the investigation to piece together what happened on the night of the attack and to find out whether others have been involved.
The suspect held in Shoreham was arrested after police entered a flat above a parade of shops in Brunswick Road in the town centre. "So you would be looking at a week today for the first charges to come about", said Hopkins.
With the intense series of police operations showing no signs of abating, a 25-year-old man is being held on suspicion of terror offences in the Old Trafford district.
New evidence has revealed that Abedi likely purchased most of the key components to make the homemade bomb himself and most of his actions leading up to last week's bombing at the Manchester Arena were carried out alone.
Gun-carrying officers swooped on sites across the city as they worked to stamp out any lingering threat from co-conspirators to Monday's massacre.
Interior minister Amber Rudd said the review was the "right first step" for the intelligence agency to take in the wake of the May 22 bombing that killed 22 people at a pop concert by US singer Ariana Grande. Andy Burnham, the mayor of Greater Manchester, and Chris Grayling, the transport secretary, were among those who laid wreaths at the station as it reopened, with Burnham paying tribute to the station's staff, who rushed to help victims of the bomb. It drew particular revulsion because of the targeting of children - the youngest victim was just eight years old, and nine of the others were teenagers. We also continue to support the families of those bereaved and the injured and our thoughts continue to be with them. There are some that clearly aren't.