'A-19-year-old man was arrested at Liverpool John Lennon Airport on Friday 7 July 2017.
Police investigating the Manchester Arena bombing have revealed that they suspect the suicide bomber responsible for the attack "did not work alone".
Russ Jackson, head of counterterrorism policing for northwest England, said police may make more arrests in the investigation into the attack.
Detective Chief Superintendent Russ Jackson, head of the North West Counter Terrorism Unit (NWCTU), said officers were "engaged" with the authorities in war-torn Libya where Hashem Abedi is now being held.
Detectives want to speak to Salman Abedi's brother in Libya amid suspicions that others may also have been involved in the attack on May 22.
But police stressed that they still did not think the attacker was part of a "large network". "We do however suspect others were either aware or complicit in the knowledge of this attack". We do believe further arrests are possible.
The suicide bomber, Salman Abedi, aged 22, was not part of a terror network, police said, but others may have known that he was going to launch an attack.
On the day of the bombing, Abedi spent several hours carrying the bomb, packed with nuts and bolts, though central Manchester before detonating it in the foyer of the arena as the Grande concert was ending. It is understood the man arrested is not Abedi's brother.
Police have found that Manchester bomber Salman Abedi was essentially financing his life with student loans, a recent report by The Sun details.
Police have previously revealed they believed Abedi had bought bomb parts just days after arriving in the United Kingdom from Turkey.