The upcoming series will star Vicky McClure, Sheridan Smith, Martin Compston and Joe Cole.
Mercurio – who also created 'Bodyguard' and 'Bodies' – reportedly got angry when a reporter broached the subject.
The BBC's Line of Duty has found an unlikely fan in the shape of best-selling author Stephen King.
The series focuses on counter terrorism policing and the work of the Metropolitan Police Bomb Disposal Squad.
As cold-hearted DCS Carmichael, Anna Maxwell Martin had fans raging - but what did she think of the final big H reveal?
'Line of Duty' creator Jed Mercurio has defended the finale episode following audience research results show 'far less extreme picture.'
The creator of the hit police drama has revealed his hint in the very first series as to which police officer was corrupt insider 'H'.
The stars of the BBC crime drama promised to all get AC12 tattoos if the show got 12 million viewers.
Martin Compston is from Greenock in Scotland, which came as a surprise to 'Line of Duty' fans.
The endless speculation about DCI Joanne Davidson's family history is over.
The man behind Ted Hastings couldn't get away from complex jargon, even on a completely different show.
The second episode of the new series of Line Of Duty marked the return of a crucial character.
The creator of the hit TV drama insists he was aiming to highlight 'police mishandling of a vulnerable suspect' with the reference.