Salman Abedi is thought to have purchased the main components for the bomb and assembled it himself before blowing himself up and killing 22 others at the Manchester Arena last week.

Greater Manchester Police said they were still working to establish if he was part of a wider network, but believe he was acting alone in the four days leading up to the atrocity.

Three of the 16 people who were in custody have now been released without charge, including a 20 and 24-year-old from the Fallowfield area and a 37-year-old man from Blackley.

In a statement a GMP spokesman said: “Our enquiries show Abedi himself made most of the purchases of the core components and what is becoming apparent is that many of his movements and actions have been carried out alone during the four days from him landing in the country and committing this awful attack.