Manchester Arena suicide bomber Salman Abedi did not act alone and carried his bomb around the city for hours before blowing himself up, police believe.

Anti-terror officers investigating the attack found explosives at a number of addresses around the city during raids after the attack, they revealed today.

Abedi, 22, detonated his bomb in the foyer of an Ariana Grande concert in May, killing 22 people, including seven children, and injuring 250.

Greater Manchester Police are currently working with authorities in Libya to speak to the bomber's brother, Hashem, who is being held by a militia in the North African country.

Investigators are also looking into whether Abedi financed his bomb-making through a student loan.

Salman Abedi killed 22 and injured 250 when he set off a bomb in the busy foyer of Manchester Arena. Police said today that they do not believe he acted alone

It emerged today that police have recovered explosives from properties in Manchester. He milled around for hours in the city centre before making his way to the venue for the attack

The explosion ripped through the arena's foyer as thousands of fans, mostly young girls and their parents, were leaving the venue following the performance.

DCS Russ Jackson, head of counter terrorism policing in the North West, said today that police were now clear on Abedi's movements in the run-up to the attack, they knew the make-up of the bomb and where parts were obtained.

He said: 'There were a number of opportunities he would have had to detonate the device.

'On that evening, we've got him at different points in Manchester. That's not all going to crowded places, but he's got it in public places, at different points, with the the backpack on.

'If we assume it's all primed and ready to go - and that would be a reasonable working assumption - there there were different points he could have done it.

'He's clearly gone to different locations. We're never going to get into this man's mind. Our assessment is that he's targeted the Arena. He wasn't looking for somewhere else that evening.

'He was out in the early part of the evening. The best we can say is for several hours before.'

Police carried out a number of raids in the days after the attack but have previously suggested Abedi acted alone. A total of 21 people have now been arrested, of which twelve people have been released without charge.

Police plan to speak to Abedi's brother Hashem. Who is being held by a group in Libya

the militia group currently holding Hashem (shown) claim he has confessed to knowing about the plot and helped his brother to buy bomb parts

DCS Jackson said today: 'We do believe that there are other people potentially involved in this. We do not believe this is part of a large network.

'We do believe that further arrests are possible. We want to speak with Hashem Abedi and we can now say we are currently engaging with the CPS and the Libyan authorities.'

Mr Jackson also told of calls Abedi made, reportedly to his mother and others, on the night of the attack were another 'key line of inquiry', Mr Jackson said, but would not be drawn further.

He said: 'Abedi was a student and we know he had access to student loans. That doesn't discount the fact he could have had money from other origins.'

He said no video or note has been found by police left by Abedi to explain his motivation.

Parents and children outside the stadium in the aftermath of the bombing in May this year

DCS Jackson added: 'This is a live criminal investigation and central to it there are 22 murdered people and grieving families. There's now more than 250 injured people - many severely - and they need to be part of the investigation.

'The searches that we conducted on average took eight days to complete. The digital exhibits we've seized contain over three million files and 15 terabytes. We have now nearly 16,000 hours of CCTV and we anticipate it will take many months to work through this.

'We have taken 755 statements and there are 3,200 people who form part of the investigation.

Police previously said they believed Abedi assembled the device by himself in the days before the attack.

They had said it was unclear whether he acted alone in obtaining materials for the bomb which officers believed were stored in a white Nissan Micra found parked in the Rusholme area of the city.

Survivors comfort each other after Abedi's bomb ripped through the lobby of the arena

It is believed that Abedi started building the detonator in a workshop at his family's address in Fallowfield in south Manchester. He is understood to have finished off the device in a second flat.

The bomber left the UK for Libya on April 15 and returned on May 18.

His brother Hashim reportedly told Libyan counter-terror forces he knew his brother was planning something and that his brother was radicalised while living in the UK two years before his deadly attack.

The bomber left the UK for Libya on April 15 and returned on May 18.