Rachel McAdams has reportedly quit her starring role in the upcoming space romance, Passengers.

The 35-year-old actress was due to replace Reese Witherspoon who had originally been cast in project.

However, according The Hollywood Reporter, McAdams has now also left the production, and the April 2015 release date for the sci-fi movie has been shelved.

Passengers, which stars Keanu Reeves, is billed as a love story between two travellers aboard a spacecraft transporting people to a colony on a faraway planet.

One passenger (Reeves) is awakened 90 years before anyone else, due to a malfunction in his sleep chambers. Fearing that he could die alone, he decides to wake up a fellow long hauler, who McAdams was set to play.

Game of Thrones director Brian Kirk had been due to commence shooting the film in Germany on April 7, but the start date has apparently been delayed by at least several weeks.