London Bridge attacker Khuram Butt worked on the Underground despite being a known extremist

One of the three terrorists who took the lives of seven people and seriously injured dozens of others near London Bridge worked for Transport for London (TfL) as recently as last year, it has emerged.

Khuram Shazad Butt, a 27-year-old British national born in Pakistan, worked on the London Underground for just under six months in 2016, despite being a known extremist.

Known to the police and MI5, Butt was a follower of the banned al-Muhajiroun network, led by the now-jailed preacher Anjem Choudary.

Butt was a British citizen and had lived in east London for a number of years. He was married with two children.

A spokesperson for TfL said: "Khuram Butt worked for London Underground for just under six months as a trainee customer services assistant, leaving in October last year."

TfL said no further comments would be made while the police investigation is ongoing.

A colleague claimed Butt was headquartered at London Bridge station but also worked at Westminster and Canada Water stations during his training programme, according to the Mail Online.

His employment at TfL ended due to poor attendance because of an injury he suffered to his leg as a child, the source said.

In January 2016, Butt appeared on the Channel 4 documentary The Jihadis Next Door, in which he was filmed praying with a black Isis flag.

Butt and two other attackers, Rachid Redouane, 30, and Moroccan-Italian Youssef Zaghba, 22, were killed by armed officers after an eight-minute rampage south of the River Thames on Saturday 3 June.