Emily Blunt has explained why she had to turn down the role of Black Widow in the Marvel films.

The part of the Avenger ended up going to Scarlett Johansson, who made her debut in the series in 2010’s Iron Man 2 and will star in the standalone Black Widow movie in July.

Blunt said she had to miss out on the part because she was contractually obliged to star in Gulliver’s Travels with Jack Black.

Speaking on The Howard Stern Show, she said: “I actually do want to clean up this story. I was contracted to do Gulliver’s Travels, I didn’t want to do Gulliver’s Travels.

“It was a bit of a heartbreaker for me, because I take such pride in the decisions that I make and it, they mean so much to me, the films that I do do. So that was tough.”

Blunt said she was obliged to the film studio to take the role opposite Black after her turn in The Devil Wears Prada.

She added: “And they kind of have a bit of a hold over you.

“So there were other movies that I would want to do and I’d say, ‘But I really want to do this movie about young Victoria.’

“And so, at some point, I think it just became evident that I needed to get rid of this optional picture deal because it was going to just hang over me for a long time and I didn’t want that.

“And ultimately, as hard as it was, I don’t think anyone expected for the hand to be forced, you hope that it isn’t.”

She added: “I care deeply about the choices that I make, that is all I have, because after that it’s really left up to the gods, what happens.

“You usually don’t really have any idea why a movie catches fire and why it doesn’t.

“But no, I’m never left with a feeling of regret when I turn something down. I know in 20 pages if I love it, it’s ethereal as to why I like it.

“I don’t know why I like it. I just love it and I’m in or I’m out after 20 pages.”

Blunt said she still made an effort to put in a good performance on Gulliver’s Travels, and said: “I was never looking like a slapped arse on set, I would never do that.

“And I also didn’t talk about it with anyone on set because there are a lot of lovely people in it who were heaven to work with and I had a really good time, I had a laugh with all of them, but it irked my heart for it to have happened in the first place, but I will always try to make the best of any situation for sure.”