He was an ex-prisoner convicted of terrorism offences and released past year, police said Saturday.
Confronted by bystanders, including a Polish man brandishing narwhal tusk he had grabbed from the wall of Fishmongers' Hall, Khan was wrestled to the ground.
Mr Merritt's father, David, paid an emotional tribute to his late son.
The developments came as the first victim of the attack, which saw three others wounded, was named as 25-year-old Jack Merritt. The group's plans included the camp in PoK, where under the guise of a madrassa they would offer arms training for attacks in Kashmir, and also a 26/11 style attack on the United Kingdom parliament.
And in March the same year, an attacker stabbed a policeman close to London's parliament buildings after a vehicle ploughed into pedestrians on nearby Westminster Bridge.
Mr. Khan was one of nine people who were imprisoned after pleading guilty to being part of a group that was plotting in 2010 to plant a pipe bomb in a toilet in the London Stock Exchange.
London Bridge was the site of an attack in June 2017 after pedestrians were run over by a van, with three men then attacking people in the surrounding area, killing eight.
'This individual was known to authorities, having been convicted in 2012 for terrorism offences.
"I'm being kept updated on the incident at London Bridge and want to thank the police and all emergency services for their immediate response", Johnson said in a statement.
British Transport police said Saturday that another man widely seen in social media videos carrying away a large bloody knife seized from the assailant is a plainclothes policeman, who helped detain the suspect and prevent further injuries.
"I have long said this system isn't working".
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Jesse Lingard was captain for the day and opened the scoring - his first goal in 28 matches - after just 10 minutes through a deflected effort.
Police said they are not actively seeking any other individuals connected to Saturday's attack, and have confirmed that it was being investigated as a terrorist incident.
And in the Labour Party, Fisher said Corbyn has faced scrutiny over his vague stances on questions of national security.
During the attack, he had been wearing an electronic tag used to monitor criminal offenders, according to a report in British newspaper The Times.
The main political parties suspended campaigning in London as a mark of respect.
Britain's Prime Minister Boris Johnson, second from right, Home Secretary Priti Patel, center, and Metropolitan Police Commissioner, Cressida Dick, left, attend the scene in central London on Saturday.
On the day of his death, Merritt was coordinating a "Learning Together" conference organized by Cambridge University academics.
A number of former programme participants, including Khan, had been invited to take part in a conference to mark the programme's fifth anniversary at Fishmongers' Hall in the capital.
The video shows one person pursuing the knife-wielding attacker with the sea creature's tusk while another sprayed the assailant with a fire extinguisher.
"We owe a deep debt of gratitude to our police and emergency services, and the fearless members of the public who put themselves in harm's way to protect others", Corbyn said late on Friday.
A White House spokesman said President Donald Trump had been briefed on the attack and was monitoring the situation.