US TV host Stephen Colbert has announced his next move after his late-night talk show ends - co-writing a new Lord of the Rings film.

Colbert, who is well-known to be a JRR Tolkien superfan, will adapt an early section of the first Lord of the Rings novel, The Fellowship of the Ring, with his son, screenwriter Peter McGee.

In a clip of a call with director Peter Jackson, Colbert said it would "be its own story that could fit into the larger story", and remain "completely faithful to the books while also being completely faithful to the movies that you guys had already made".

TV network CBS announced the cancellation of Colbert's late-night show last summer, and it will end in May after 33 years.

Colbert said he came up with the idea for the film, reportedly titled The Lord of the Rings: Shadow of the Past, but "did not think I would have the time" to work on it.

"As much as I love it, I knew I couldn't do that [film] and do the show at the same time. But it turns out I'm going to be free starting this summer."

Colbert is planning to adapt chapters three to eight of The Fellowship of the Ring, in which Frodo and his fellow hobbits begin their epic quest.

"You know what the books mean to me and what your films mean to me," Colbert told Jackson.

"But the thing I found myself reading over and over again were the six chapters early on in the Fellowship that y'all never developed into the first movie back in the day."

He added: "I started talking it over with my son Peter, who's also a screenwriter, and we worked out what we thought would work, especially as a framing device for that story."

The film's official synopsis says: "Fourteen years after the passing of Frodo, Sam, Merry and Pippin set out to retrace the first steps of their adventure. Meanwhile, Sam's daughter, Elanor, has discovered a long-buried secret and is determined to uncover why the War of the Ring was very nearly lost before it even began."

Colbert told Jackson it "took me a few years to scrape my courage into a pile to give you a call", but he did so two years ago and Jackson liked his idea.

Colbert is now working with McGee and Philippa Boyens, who co-wrote the previous Lord of the Rings and Hobbit films.

Boyens is also co-writing the next Lord of the Rings-related release, The Hunt for Gollum, which is being directed by Andy Serkis and is scheduled for release in 2027.

Jackson directed the hugely successful Lord of the Rings film series more than 20 years ago, winning best director and best picture at the Oscars for The Return of the King in 2004.

That was followed by the Hobbit film trilogy and a big-budget Amazon Prime TV spin-off.