John Lithgow will star in 'Pitch Perfect 3'.

John Lithgow

John Lithgow

The 'Crown' actor - who has an extensive background in musical theatre - has signed up to appear in the third installment of the popular musical comedy, Variety reports.

Plot details for the latest saga involving a cappella group Barden Bellas is being kept under wraps, so it hasn't been revealed what role John, 71, will play in the movie.

Trish Sie is directing the film from a script written by Kay Cannon, assisted by Mike White and Dana Fox and some of the cast revealed last month they had begun filming.

Rebel Wilson - who plays Fat Amy in the movie - shared a photo on Instagram with her co-stars Anna Kendrick and Brittany Snow and captioned the image: "#PP3 #Bellas Day One Pitches x (sic)."

And 31-year-old Anna, who plays the role of Beca Mitchell in the production, also shared the same photograph on her social media page.

She wrote: "Team. (sic)."

And Brittany - who plays Chloe Beale in the franchise - recently teased the third instalment of 'Pitch Perfect' is "just around the corner".

Alongside an image of the blonde beauty with a few of the other Bellas including Elizabeth Banks, she wrote: "#PP3 is just around the Corner (sic)."

And it is believed Ruby Rose is also set to feature in the film, which will be released in December this year.

However, Skyler Astin - who played Anna's on screen boyfriend and lead singer of a cappella group The Trebles, Jesse Swanson - has revealed he and the rest of the all-male vocal group won't feature in 'Pitch Perfect 3', despite appearing in both 'Pitch Perfect' and 'Pitch Perfect 2'.

He previously tweeted: "Yes. As of now, the Trebles and I won't be in the third Pitch Perfect movie. They seem to be taking the story in a different direction (sic)."