Amanda Seyfried says she has 'nightmares' about her 'weak singing' in 'Les Misérables'

• Amanda Seyfried said she "regrets" her role as Cosette in "Les Misérables."
• She told Vanessa Kirby she thinks her singing in the movie was "weak" and has "nightmares" about it.
• Seyfried said she could play Cosette now as she has worked "diligently" to improve her singing.

Amanda Seyfried says she still has "nightmares" about her performance in "Les Misérables" and wishes she could "redo" the role today.

Seyfried was talking with "The Crown" alumni Vanessa Kirby for Variety's "Actors on Actors" series, and Seyfried told Kirby she regrets her performance as Cosette in the Oscar-winning movie - an adaption of the world-famous stage musical.

"I have had a lot of moments where I just felt complete regret. I wish I could redo 'Les Misérables' completely because the live singing aspect, I still have nightmares about it," Seyfried said.

The actress, who has also sung in "Mamma Mia!" and its sequel, said her voice wasn't as strong as it needed to be: "I was very weak."

Directed by Tom Hooper, the movie famously utilized live-singing while the cast filmed their scenes as opposed to the more traditional method of recording songs in a studio and playing them back on set for the actors to lip-sync to. Seyfried didn't mention this as a reason for feeling unhappy with her performance, but she did say she feels she could "definitely play Cosette now."

"I've been working diligently ever since 'Les Mis' to work on strengthening my voice and have some kind of stamina, working on my vibrato, which was just completely lost," Seyfried said. "From a very technical standpoint, I was very unhappy with my singing."

"Les Misérables" was a success, though, earning eight Oscar nominations including best picture and best actor for Hugh Jackman, plus a best supporting actress win for Anne Hathaway, who played Fantine.

Seyfried is in the running for an Oscar herself this year thanks to her acclaimed turn in Netflix's "Mank." She stars opposite Gary Oldman and is competing for a best supporting actress nomination.

Vanessa Kirby, meanwhile, said she would be "terrified" to sing live like Seyfried did and thought the "Mean Girls" actress sounded "incredible" in the movie. Kirby is also in the mix for an Oscar nomination, with her leading role in another Netflix movie - "Pieces of a Woman."

Watch the full interview below: