Martin Scorsese was stunned that 'The Departed' won him an Oscar for Best Director.

The legendary director explained that the 2006 film was made as his farewell to big-budget moviemaking and it took him by surprise that it gave him his only personal Academy Award triumph to date.

In an interview with The New Yorker, Scorsese said: "I had made 'The Departed' as a sign-off.

"I was leaving and just going to make some small films, I don't know. And it just happened that 'The Departed' clicked. And it was a very difficult one to make, for many different reasons. That's a whole other story.

"But we fought our way out of it – through it, I should say. Through it, out of it. And, when I finally threw it up on the screen, people liked it."

The 'Killers of the Flower Moon' director added: "I don't mean I didn't think it was good or bad. I just felt we had accomplished something. I didn't know it was going to be that way. I had no idea."

The 80-year-old filmmaker explained that he was hesitant about making 'The Departed' – which starred Leonardo DiCaprio, Matt Damon and Jack Nicholson – after the "very, very" ugly distribution issues with 'The Aviator' but explained that the script for the crime thriller resonated with him.

The 'Casino' director recalled: "I found the script of 'The Departed' and I liked the idea and I said, 'Let's just make this in the streets and let's do something.'

"I was able to make 'Departed' pretty much the way I wanted to. But it was a knockdown, drag-out fight all the way from Day One to the end. So by that point I realised, if that's the way you're going to make a film, there's no sense anymore."

Scorsese continued: "Winning the award was – don't forget, it was thirty-seven years before an Oscar for Best Director, let alone Best Picture, which was a total surprise to me. But it's a different Academy from when I was starting. But, for me, that award was, it was inadvertent."