Star Wars: Episode IX director JJ Abrams has paid tribute to Carrie Fisher as filming begins, with the late actress set to posthumously appear in the blockbuster thanks to previously unseen footage.

Abrams, who worked with Fisher on Star Wars: Episode VII, The Force Awakens, said it was "bittersweet" to begin filming on Wednesday at London's Pinewood Studios without the actress in front of the lens. 

Sending his first tweet with a photo of a camera on the Episode IX set, Abrams wrote: "Bittersweet starting this next chapter without Carrie, but thanks to an extraordinary cast and crew, we are ready to go."

"Grateful for @rianjohnson [Star Wars: Episode VIII director] and special thanks to George Lucas for creating this incredible world and beginning a story of which we are lucky to be a part. #IX," he added. 

Last Friday, it was announced that previously unseen footage of Fisher from The Force Awakens would feature in Episode IX.

Carrie Fisher as Leia in The Force Awakens

In a statement on Friday, Abrams said: "We desperately loved Carrie Fisher. Finding a truly satisfying conclusion to the Skywalker saga without her eluded us. We were never going to recast, or use a CG character.

"With the support and blessing from her daughter, Billie, we have found a way to honour Carrie's legacy and role as Leia in Episode IX by using unseen footage we shot together in Episode VII."

Carrie Fisher suffered a heart attack on December 23, 2016 while on a flight from London to Los Angeles and died in hospital on December 27. She had completed her filming for 2017's Star Wars: The Last Jedi shortly before her death.

Star Wars makers Lucasfilm also revealed the rest of the cast for Episode IX last week, with Billy Dee Williams set to reprise his iconic role as Lando Calrissian and Withnail & I's Richard E Grant, The Americans' Keri Russell and Lady Macbeth's Naomi Ackie joining the ensemble.

Our man in a galaxy far, far away - Domhnall Gleeson is back as General Hux

Domhnall Gleeson will return alongside Daisy Ridley, Mark Hamill, Adam Driver, John Boyega, Oscar Isaac, Lupita Nyong'o, Kelly Marie Tran, Anthony Daniels, Joonas Suotamo and Fisher's daughter, Billie Lourd.

Star Wars: Episode IX will be released on December 20, 2019.