People take part in a vigil for the victims of an attack on concert goers at Manchester Arena, in central Manchester, Britain, May 23, 2017.
Anti-terror officers also confirmed on Thursday they want to speak to Salman Abedi's brother Hashem in Libya as part of the "ongoing" process of the investigation.
It comes a day after detectives said they believed the bomber did not act alone when preparing the deadliest attack on United Kingdom soil since the 7/7 bombings exactly 12 years ago.
Twenty-two people were killed May 22 when Abedi, a Briton of Libyan heritage, detonated a homemade knapsack bomb as crowds were leaving an Ariana Grande concert. It is understood the man arrested is not Abedi's brother.
Russ Jackson, the Chief Superintendent in charge of the investigation, believes others were "aware or complicit" and they're still creating a full account about his life, beliefs and background.
He did say there was no evidence of other potential suicide bombers on the night.
And Mr Jackson did not rule out further arrests.
Investigators have trawled through three million files and 16,000 hours of CCTV footage as they try to trace Abedi's movements in the days and weeks leading the bomb blast.