Egyptian director Mohamed Diab broke out internationally with bold sex harassment pic “Cairo 678” in 2010. That was before the Tahrir Square protests in 2011 and Egypt’s ensuing revolution, which prompted him to become a passionate social media activist. In “Clash,” which opens Thursday  in Cannes’ Un Certain Regard, Diab delves into Egypt’s religion-related political turbulence.

How did “Clash” come about?
When I became an activist during the Egyptian revolution I became so involved that I stopped making movies for a couple of years. Then I started thinking: “This is what I want to write about.” But things were moving so fast that every story that came to me was becoming old before I finished writing it. So about four years went by before my brother came up with this idea of cramming people in a police truck and how that would represent a big opportunity to express what we really feel about what’s going on in Egypt.

Of course there is lots of interest outside of Egypt in gaining an understanding of the Arab world that you can’t get from CNN. What would you say are some of those things might be in your film?
I wanted to make it as universal as possible, yet it had to express us [Egyptians]. So I tried to examine the origins of violence from every side. From the authorities’ side, from the extremists’ side, from the activists’ side. You see how the vicious circle is fed, how it gradually grows and how that circle is the reason for violence on all sides.

Was “Clash” difficult to shoot?
Very. You are risking your life because people might mistake the shoot for a protest, or might mistake you for the police. And there are haters of both, who can shoot you. It took us months of preparation. Egyptians to whom I’ve shown the film to are blown away because they know that what we did is almost impossible.