The suicide bomber reportedly returned from Libya only a few days before the attack which killed 22 people including several children.
One woman arrested by armed police on Wednesday was released a few hours later without charge, leaving 10 men still in custody Thursday, including suspected killer Salman Abedi's father and brother in Libya.
Abedi reportedly returned from Libya only a few days before the attack which killed 22 people including several children but police are still trying to pin down his movements as well as a wider network.
Here are the details of the arrests so far:
- A 23-year-old man is arrested by masked police in the Chorlton area of south Manchester near where Abedi is believed to have lived. An eyewitness told AFP police shouted at the man to lie on the ground before taking him away. British media indicated this is highly likely to be Abedi's older brother Ismael.
The brother was described in media reports as "outgoing" compared to Salman, who was "very quiet".
- Police arrest three more men in south Manchester, a short walk from the house where Abedi lived.
Omar Alfaqhuri, a neighbour who lives just in front of a house that was raided, said he saw "a massive deployment of police forces" during the arrest in the night and a man he named as "Adel" taken away.
"They blocked the whole street," he said, adding that he saw the man handcuffed and taken away in a car.
He said his neighbours were a "nice quiet family".
- A man, who police said was carrying a suspect package, is arrested in Wigan, a town near Manchester.
- Another man is arrested in the town of Nuneaton in central England, widening the British police probe from areas in and around Manchester.
- Libya's Deterrence Force, which acts as the police of the Tripoli-based Government of National Accord, arrest Abedi's father Ramadan, saying they had already arrested his brother Hashem on Tuesday.
A spokesman said the brother was aware of Abedi's attack plan and both belonged to the Islamic State group, which claimed responsibility for the attack.
Abedi's father reportedly protested his son's innocence in the hours before his arrest.
- In Manchester, a woman is arrested in an apartment block in Blackley, an area north of the city centre by armed police. She is later released without charge.
- A man is arrested in Withington, a suburb of south Manchester. Another man is arrested in the Manchester area, police said without giving further details.
- In the early hours of the morning, a controlled explosion is carried out during a police search at a property in the Moss Side area of Manchester.