The Hobbit director has revealed that Fortitude actor Robbie Sheehan and Fantastic Beasts and Where to Find Them's Ronan Raftery will appear in the film adaptation of Philip Reeve's novel of the same name.

Details of their characters have yet to be revealed, but according to Variety, Sheehan is playing a lead character and Raftery is taking on a supporting role.

It has also been reported that studios Universal and MRC are hoping to start production this spring (17), in Jackson's home country of New Zealand, with the film slated for release on 14 December, 2018.

First published in 2001 by Scholastic, Reeve's Mortal Engines books have won several prestigious awards including the Guardian Children's Fiction Prize, the Los Angeles Times Book Award and the Blue Peter Book of the Year. The series focuses on a futuristic version of the world in which cities roam the globe on huge wheels, with each striving to survive while quickly running out of resources.

Jackson, Fran Walsh and Philippa Boyens, who co-wrote both The Lord of the Rings and Hobbit trilogies, are all collaborating on the screenplay adaptation for Mortal Engines.

However, Jackson will not be taking the helm on the film, as Christian Rivers, who has worked as a visual effects supervisor for the director's Weta Digital, will make his feature directorial debut with the project.

In addition to U.K. TV series Fortitude, Sheehan can be seen next in the movie Geostorm. No stranger to fantasy adaptation, he also portrayed Simon in the 2013 fantasy adaptation The Mortal Instruments: City of Bones.

Raftery most recently starred in Netflix war drama The Siege of Jadotville and will next be seen in the AMC anthology show The Terror.

The sci-fi movie is the first in a planned series of films based on Reeve's novels. The series is comprised of four books: Mortal Engines, Predator's Gold, Infernal Devices, and A Darkling Plain.