He was seized 90 minutes later in a raid on a house in Birmingham in the English Midlands.
Andrew Parker, the head of the MI5 revealed the plot to the Cabinet. Imran is accused of trying to get a false passport in an effort to go to Libya to join a group linked to the Islamic State.
A Scotland Yard spokesperson declined to confirm to The Independent whether the arrests were linked to a plot to attack the prime minister.
On Tuesday MI5 revealed that it had prevented nine terror attacks in the United Kingdom in the past year but several attackers have still got through.
MI5 has prevented nine terror attacks in the United Kingdom within the past year, director Andrew Parker said Tuesday, according to The Guardian. The report confirmed that the ringleader of the London Bridge knifing spree had been under investigation by MI5. Bomber Salman Abedi killed 22 people when he blew himself up outside an Ariana Grande concert. Authorities say at least nine more were foiled.
Security measures were introduced in the 1970s but were increased in the 1980s as the threat from Irish republican groups grew.
Naa'imur Zakariyah Rahman, 20, allegedly had an explosive device in his bag and planned a bomb assault on the prime minister's residence.
The IRA had previously targeted prime minister Margaret Thatcher at the Conservative conference in Brighton in 1984.