Jonathan Hacker, director of the hard-hitting documentary Path of Blood, has defended his decision to use of footage shot by al-Qaida terrorists.

Hacker, who is a Bafta-award winner, is set to see his film hit the cinemas next week. In it, the documentary decided against the use of a narrator and instead uses brutal footage filmed by terrorists planning to detonate car bombs in the Saudi capital, Riyadh.

“People say ‘don’t give terrorists air time’, but what they should say is ‘understand these people’. Only by understanding the nature of their faith, the nature of their psychology will you be able to combat them,” Hacker told The Guardian.

The footage, which has been seized by Saudi military forces, were found at a jihadist training camp in the desert and amounted to over 500 hours of content – all of which Hacker himself had dissected in order to piece together to make Path of Blood.

“It was a mammoth, mammoth task,” Hacker added. “The translating alone took five months because there was so much jargon, slang and thick accents.

“You see that these terrorists are incredibly young, incredibly naive, many of them incredibly stupid, but all of them still capable of great evil.

“If you put this stuff into a drama you wouldn’t believe it. You’d say that it’s not plausible, that it doesn’t make sense,” he continued.

The footage, which is harrowing and disturbing in equal measure, covers a varied amount of topics from terrorists playing football to the same terrorists torturing American hostage Paul Marshall Johnson.

“I felt with this particular scene, what was important was the line of questioning. While it is unbearably painful it tells you a lot about their mindset,” Hacker said of the scene involving Johnson. “That’s part of the story, that’s part of what it means to understand who these terrorists were.”