Updated

A Libyan counterterrorism official said Thursday that the brother of the Manchester arena suicide bomber knew he was planning something, and that his radicalization took root when he was living in the city in 2015.

Libyan official Ahmed bin Salem said that Salman Abedi's brother Hashim was still being held for questioning in Libya. Abedi's father, who allegedly belonged to an al-Qaida-backed extremist group, is also being held there.

Abedi blew himself up at the Manchester arena last month, killing 22 people.

Manchester police said Thursday that a 20-year-old man had been arrested in connection to the investigation of the concert attack. Police said he "voluntarily presented" himself to police Wednesday night and was arrested on suspicion of violating the Terrorism Act.

He has not been charged or identified. Police have nine people in custody for questioning.

Libyan officials say there is no connection between Abedi and the attackers in the more recent deadly assault in the London Bridge area.