The Housemaid's Amanda Seyfried didn't know she was exec producer until 3 weeks into filming

The Housemaid star Amanda Seyfried didn't know she was an executive producer on the movie - until three weeks into filming.

The 40-year-old actress was stunned to see a call sheet with her name listed as "executive producer", and she was later told it was a position her agent had negotiated.

Speaking about her production credit on the film, she said on The Graham Norton Show: "I’m a producer on it and I didn’t know until three weeks in.

"I saw the call sheet and I was like, ‘Executive producer? I didn’t sign up for that.’

"I called one of the producers and was like, ‘You guys have me on as an executive producer.’

"And he was like, ‘That’s what your agent negotiated.’

"And I was like, ‘Well this really better be a hit then.' "

But Seyfried now believes it was a "vanity credit", because she didn't anything production-wise to make the film.

She added: "It was one of those vanity credits, because I didn’t do s**t to make that movie. I only acted in it.

"That’s the thing about vanity credits. I don’t want people to get it twisted."

Amanda compared herself to Margot Robbie, but admitted the Wuthering Heights star is often "really intensely" involved in films from the start.

She said: "What Margot [Robbie] does is really intensely develop movies from jump."

But Amanda - who appeared alongside Sydney Sweeney in the movie - insisted she just "had a bunch of fun" acting in the motion picture, "and left".

She added: "I just jumped in, had a bunch of fun and left. And now, I’m like, they’re sending me on a vacation."

Last month, Seyfried told how she felt "so liberated" while making The Housemaid.

She explained to W Magazine: "I star opposite Sydney Sweeney, and we have the same shoe size, are the same height, and we giggle the same way.

"It was so crazy - in some ways, that film is like Black Swan or Single White Female, but funny. I got to play so hard.

"The director, Paul Feig, would give me the strangest directions. He’d say, 'Okay, make [Sydney] think you’re going to kiss her!' I felt so liberated."