Pak-born British terrorist was brainwashed by extremist group al-Muhajiroun

Khuram Shahzad Butt is familiar to UK police and was already investigated in 2015

A 27-year-old Pakistan-born British national, who was shot dead by police after the London attack, was a brainwashed follower of a banned extremist group and known to intelligence agencies, media reports said on Tuesday.

British officials confirmed that Khuram Shahzad Butt, one of the three attackers who launched a van and knife attack in central London Saturday night, was a member of the al-Muhajiroun extremist group with links to the jailed preacher Anjem Choudary.

He was born in Pakistan but brought up in the UK and was known to police and had been investigated in 2015.

The Metropolitan Police have defended a decision to downgrade an inquiry into Butt, saying they did not have any evidence of a plot.

They said Butt was known to police and MI5 in 2015, but there had been no evidence of a plot.

Metropolitan Police assistant commissioner Mark Rowley said an investigation into Butt began in 2015, but "there was no intelligence to suggest that this attack was being planned and the investigation had been prioritised accordingly".

The inquiry was "prioritised in the lower echelons of our investigative work", Rowley was quoted as saying by the BBC.

Asked if that had been a poor decision, Rowley said he had seen nothing yet to suggest it.

The two other perpetrators were not known to security services.

Police today identified the third attacker as Youssef Zaghba, a 22-year-old Italian of Moroccan descent, a day after naming his accomplices as Butt and Rachid Redouane, 30, a self-described Moroccan-Libyan dual national.

Butt had appeared in a Channel 4 documentary, The Jihadis Next Door, and had been reported to the anti-terrorism hotline for extremism.

Butt was linked to al-Muhajiroun, the banned extremist group whose leader, Choudary, was jailed last year for encouraging support for Islamic State.

Butt, who lived in Barking in east London, appeared several times in a 2016 Channel 4 documentary called "The Jihadis Next Door," which profiled a group of individuals linked to al-Muhajiroun in the United Kingdom.

At one point in the documentary, he can be seen helping unfurl a black banner in Regent's Park after a radical preacher promised it would fly one day over 10 Downing Street, the headquarters of the Government of the United Kingdom.

Transport for London has confirmed that Butt worked as trainee customer services assistant for six months last year.

One colleague, quoted by the Guardian, claimed that as part of the training programme he was headquartered at London Bridge station and also worked at Westminster and Canada Water stations.

CNN reported that Butt went by the name "Abz" or "Abu Zaitun".

At the time of the attack, Butt worked as a receptionist at a fitness centre in Ilford, a friend from the gym said.

The gym is described as a mixed martial arts gym on its website. Butt told the friend he had stopped attending al- Muhajiroun meetings some time ago.

Al-Muhajiroun has been linked to half of all terror plots by British nationals in the United Kingdom and overseas over the last two decades, according to research published in 2015 by Raffaello Pantucci, a terrorism analyst at the Royal United Services Institute.

Several followers of the group joined ISIS in Syria including Abu Rumaysah and Abu Rahin Aziz, a Luton, England, resident killed in a US drone strike in Raqqa, Syria, in July 2015.

Al-Muhajiroun's longtime UK leader Anjem Choudary was convicted and sentenced to five years in prison in 2016 for calling on Muslims in the United Kingdom to support ISIS.

The identification of Butt as one of the attackers raised many questions about what British authorities knew about him and when.

Mohammed Shafiq, chief executive of the Ramadhan Foundation, said that after confronting Anjem Choudary for his support for terrorism near the Houses of Parliament a day after Lee Rigby's killing he was called a "traitor" by the future London attacker, Butt.

"Many of us in the British Muslim community have been demanding action against these extremists to no avail. I am not surprised that Khuram Butt carried out the terrorist attack and there are serious questions for the authorities," Shafiq stated.