The move to scale back the threat level from critical to severe was announced by Prime Minister Theresa May who said there were now 11 suspects in custody over Monday night’s bombing targeting young fans at a pop concert.

Investigators gave details of Abedi’s last hours as they released photographs from security cameras showing the bespectacled suicide bomber in trainers, jeans, black sleeves, a black cap and a black puffer waistcoat, over which the straps of his backpack can be seen.

The 22-year-old, of Libyan origin, was born in the northwestern English city.

The police statement said one of the last places he went to was a “city centre flat and from there he left to make his way to the Manchester Arena,” where the attack took place.

“The flat is highly relevant as a location which we believe may be the final assembly place for the device.”

Two unarmed police officers remained on guard outside the entrance to Granby House, believed to contain the flat in question, according to an AFP correspondent at the scene.

“It is surprising, because these people are just under your nose and you don’t know it,” said Harpreet Lota, a Manchester resident walking past the building.

In their latest arrests over the attack, police detained two men, aged 20 and 22, in an early morning raid in north Manchester on Saturday.

Along with the 11 suspects in UK custody, police in Libya have detained Abedi’s father and brother.

A third of those killed in Monday’s bombing were children, and another 116 people were injured.

The attack, which has been claimed by the Islamic State jihadist group, targeted concertgoers at the end of a show by US teen pop idol Ariana Grande.

British counter-terror chief Mark Rowley said Friday that police had captured “a large part of the network” linked to the bombing.