They included seven women and five men who were arrested following the attack, while a 55-year-old man and 53-year-old woman arrested at the same address in Barking have been released.
The Italian mother of one of the London Bridge attackers said Wednesday her 22-year-old son became radicalized in Britain, falling under the spell of Islamic extremism and confiding to her that he had dreams of moving to Syria.
Last year, Zaghba was stopped at the airport in Bologna on his way to Istanbul and was put on an EU-wide database but was not prosecuted.
Mayor of London Sadiq Khan said there had been a spike in “racist incidents” following the attack and has warned that police will take a “zero-tolerance approach to hate crime”. Several British media reports on Tuesday, however, said he had been denied political asylum in Britain in 2009 but allowed to work years afterward in Ireland after he married his British wife. He had slipped down in priority because there was no intelligence he was planning an attack.
Butt wore an Arsenal shirt and a fake suicide belt during his bloody spree and was later pictured sprawled on the concrete outside the Wheatsheaf pub.
NHS England said 36 people remained in hospital, with 18 in a critical condition.
Seven people were killed and nearly 50 injured when three attackers ran down pedestrians on the bridge, then stabbed passers-by in nearby Borough Market.
According to the newspaper, he had recently found a part-time job at a restaurant in London.
Authorities say the threat is unprecedented, with 500 active investigations involving 3,000 individuals in addition to 20,000 former subjects of interest.
During his time in Britain, Butt once worked for Transport of London as a customer service clerk but failed his probation after a few months on the job after attendance issues.
Butt, a 27-year-old British national born in Pakistan, had appeared in a British TV documentary broadcast last year called “The Jihadis Next Door”.
The arrest followed a raid at a property that is still being searched.
One of the messages behind the training is “run, hide, tell”, in case of an attack.
The Islamic State jihadist group claimed Saturday’s attack.
He changed his profile picture to a message from the holy book of Islam, which read: “Speak justice, speak kindly, speak politely, speak fairly, speak gently, speak graciously, speak not in vain”. Since the attack, he has said he fully supported the actions of the police.
Police say he was not a “subject of interest” to police or the intelligence services.
Foreign Secretary Boris Johnson acknowledged authorities will face questions.
Gabrielli said: “We have our documents and conscious clear, but because we are also responsible people, we can understand the concern, the suffering and the difficulty of those who are called to manage complicated situations”.
As details about the jihadists have emerged, Prime Minister Theresa May has faced questions about her record overseeing cuts to police numbers when she was interior minister.
“I feel like I did what any other person would have done”, he said.
He has been criticized for voting against counter-terrorism legislation and expressing reservations about police responding to attacks with “shoot-to-kill” tactics.
Australian nurse Kirsty Boden, 28, Canadian national Christine Archibald, James McMullan, who lived in Hackney, east London, Australian nanny Sara Zelanak, 21, and French waiter Alexandre Pigeard, 27, were among those who died in the atrocity.