MI5 'must answer questions on London attacker', Boris Johnson says

Former London mayor Boris Johnson has said questions need to be answered over the monitoring one of the London attackers.

Counter-terror agencies are facing scrutiny after it emerged that Khuram Shazad Butt was investigated in 2015, but was "prioritised in the lower echelons" of investigate work after officers found no evidence to suggest an attack was being planned.

He also appeared in Channel 4 documentary The Jihadis Next Door last year.

The Foreign Secretary told Sky News: "People are going to look at the front pages today and they're going to say 'how on Earth could we have let this guy or possibly more through the net?'

"'What happened, how could he possibly be on a Channel 4 programme and be committing atrocities like this?'

"That is a question that will need to be answered by MI5, by the police, as the investigation goes on."

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Metropolitan Police Assistant Commissioner Mark Rowley defended the actions of the security services.

He said: "At any one time MI5 and police are conducting around 500 active investigations, involving 3,000 subjects of interest.

"Additionally, there are around 20,000 individuals who are former subjects of interest, whose risk remains subject to review by MI5 and its partners."

Security agencies and the police have failed 18 terror plots since 2013, including five since the Westminster attack in March.

Theresa May said she expects police and the security services to carry out a review following the London Bridge attack.

But she sidestepped questions on whether Mr Johnson was right to say the public would have concerns over how the attackers were missed.

She told Sky News: "MI5 and the police have already said they would be reviewing how they dealt with Manchester and I would expect them to do exactly the same in relation to London Bridge.

"What Government needs to do is, and what the Government that comes in after Thursday's election needs to be willing to do, is to give more powers to the police and security service when they need them, needs to deal with this issue of terrorism and extremism online and also needs to be able to call out extremism here in the United Kingdom."

Butt, who also went by the name Abu Zaitun, was allegedly an associate of radical hate preacher Anjem Choudary and was also reported to the anti-terror hotline in 2015 for showing signs of "extremism or radicalism", Mr Rowley said.

Transport for London confirmed Butt worked for London Underground for just under six months as a trainee customer services assistant, but left in October last year.

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Meanwhile, the chairman of the mosque where one of the other London attackers worshipped has told of his shock.

Sunawar Ali said that he remembered Rachid Redouane as "quiet" and "gentle".

Mr Ali said he had last seen Redouane about two weeks ago but did not speak to him, nor did he see anyone else speak to him.

He told Sky News that Redouane was "quiet ... hasn't made any problems".

When Mr Ali was told Redouane, 30, had been involved in the terror attack, he said: "Wow, I feel very sad but I don't believe how this happened.

"I've got no clue why and how so really I'm shocked now.

"This sort of thing... security should be updated if this is the fact."

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Redouane claimed to be Moroccan and Libyan but was also known to have lived in the Rathmines area of Dublin, Ireland, for 18 months until last year.

Security sources in Ireland confirmed Redouane married a British woman in Dublin in 2012 and also went by the name Rachid Elkhdar.

The third attacker has been identified as 22-year-old Moroccan-Italian Youssef Zaghba, according to Sky sources.

The Corriere Della Sella newspaper reported that Zaghba was stopped in Italy in 2016 trying to get to Syria and Italian authorities allegedly tipped off the UK about his movements.

An Italian intelligence source confirmed he has an Italian mother and a Moroccan father, Reuters reported.

As well as using a van and knives in their murderous spree, the terrorists are also believed to have had a stock of at least a dozen Molotov cocktails in the back of the vehicle.

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Police confirmed that 12 people arrested in connection with the attack on Sunday have now been released without charge. They had detained seven men and five women and also searched six properties as part of their investigation.

A further raid was carried out by Metropolitan Police officers at a property in Ilford, East London, on Tuesday.

Seven people were killed in the attack. Of the 48 people taken to hospital, 36 are still receiving treatment, with 18 of those in a critical condition.

The third victim of the attack has been identified as nurse Kirsty Boden, who was killed after running to help people on London Bridge.

In a statement, her family said: "As she ran towards danger, in an effort to help people on the bridge, Kirsty sadly lost her life.

"We are so proud of Kirsty's brave actions which demonstrate how selfless, caring and heroic she was, not only on that night, but throughout all her life.

"Kirsty - we love you and we will miss you dearly."