Greater Manchester Police said a 19-year-old man had become the latest suspect detained over Monday’s atrocity, which left 22 dead.
He was arrested during an armed swoop on an address in the Gorton area of the city. A 25-year-old man was earlier held on suspicion of terror offences in the Old Trafford district.
A search was also carried out in Moss Side as part of the investigation yesterday.
Twelve people are now in custody after the atrocity at the Manchester Arena left 22 dead.
The latest operation came hours after the Home Secretary warned members of bomber Salman Abedi’s terror network could still be at large.
Amber Rudd said parts of the suicide attacker’s circle were “potentially” unaccounted for, despite optimism that a previous wave of arrests had quelled further threats. As the counter-terror operation continued, the NHS said 54 people were still being treated in eight hospitals with 19 receiving critical care.
Earlier, thousands of runners took part in the Great Manchester Run and a vigil for the victims was held in Wakefield Cathedral.