Pablo Schreiber had extensive military training for his role in 'Den of Thieves'.

The 39-year-old 'Orange is the New Black' actor stars as Ray Merrimen alongside Gerard Butler in the new movie by Christian Gudegast and Schreiber revealed the cast had to push themselves when it came to physical workouts.

In an interview with Den of Geek, Schreiber said: ''They left the physical side and the workouts to us, I mean with the weapons training, we had extensive military movement, team movement, weapons training boot camp, a couple of weeks before we started shooting. But in terms of physical fitness and conditioning that was left to us. So yeah, it was every man for himself and I think everybody knew that everyone else was doing their best to get in shape, so it kind of pushed everyone else to do better!

''Yeah, there was actually two separate boot camps, there was what they were doing for the cops which was a little bit more basic and a little more geared towards the kind of training they would receive. And then there was what they did for us, because Enson (50 Cent) and Merrimen in particular come from a MARSOC marine background, which is a highly specialised branch of the special forces of the military, so, the kind of training they would receive is a lot more technical and specific. The weapons they use are different, the way they move as a team is very different.''

The new film follows hard-drinking Nick O'Brien (Butler) who is the leader of the Regulators, an elite unit of the Los Angeles County Sheriff's Department.

Merrimen (Schreiber) is the recently paroled leader of the Outlaws, a gang of ex-military men who use their expertise and tactical skills to evade the law.

O'Brien, Merrimen and their crews soon find themselves on a direct collision course as the criminals hatch an elaborate plan for a seemingly impossible heist.