A 20-year-old man has been arrested in connection with the Manchester Arena bombing after handing himself in to police.
He voluntarily presented himself at North Manchester Police Station on Wednesday and was detained on suspicion of terror offences, Greater Manchester Police said.
As it stands 21 people have now been arrested in connection with this investigation, of which 12 people have been released without charge.
Nine people remain in custody.
Two of the other arrests came on Tuesday, with a 20-year-old being arrested in Harpurhey, and a 38-year-old being detained at Heathrow Airport as part of a planned operation, both on suspicion of terrorism offences.
Last month's atrocity left 22 people dead, including seven children, and scores injured.
The inquests into the deaths of the victims are due to begin on Friday at 10.30am.
They will be opened at Manchester Civil Justice Centre by senior coroner for Manchester Nigel Meadows.
The hearings are expected to be adjourned pending the completion of the police investigation.
An inquest into suicide bomber Salman Abedi's death will be opened at a later date.
On Tuesday, police said he may have stored items used to assemble his improvised explosive device in a Nissan Micra.
GMP said "significant evidence" was found in the white car, which has an "R" registration plate and was seized from Devell House in Rusholme on Friday.
The force issued photos of the car and a red and black holdall and appealed for anyone who recognised either to come forward.
Detective Chief Superintendent Russ Jackson said police were continuing to track the movements Abedi made in the days leading up to the May 22 attack.
He said: "Our investigation has also revealed that Abedi made repeated trips to and from this car between May 18 and 22 and we believe he was taking items from the car to help assemble the device.
"The car was sold by a previous keeper on April 13 2017.
''Abedi left the country on April 15 and it is vital that we understand what happened to this car during these few days between April 13 and 15."
On Tuesday, a police officer outside the flat of Abedi's brother Ismail in nearby Whalley Range told reporters that the property was still "an active crime scene".
Abedi, whose family are of Libyan origin, died after detonating an improvised explosive device as people began leaving a show by US singer Ariana Grande.
On Tuesday an 18-year-old man - understood to be Abedi's cousin - and two other men were freed.
Ismail, 23, was released on Monday, while his other cousins, Isaac Forjani, 24, and Abz Forjani, 21, both from Fallowfield, were among those released last week.
The attacker's father, Ramadan Abedi, was arrested in Tripoli on May 24, along with Salman's younger brother Hashim, 20, who Libyan security forces said were "aware of all the details" of the attack.
Islamic State claimed responsibility for the atrocity.