The new sci-fi thriller "Looper" is being hailed by critics.

Bruce Willis shows that he is not too old to be an action star in the first full-length trailer for the time travelling thriller Looper.

In Rian Johnson's mind-bending science fiction story, Joseph Gordon-Levitt plays an assassin in a world where the mob sends targets back in time to be killed, thereby leaving no evidence of the crime.

Gordon-Levitt's world is turned upside down when a target is sent back to him and he realises that the man he has been ordered to kill is his future self, played by Willis.

Director Johnson first caught the eye of the critics with Brick, a dazzlingly original noir thriller set within a high school, which also starred Gordon-Levitt. His last film, crime caper The Brothers Bloom, failed to set the world alight, but Looper is highly anticipated as a return to form.

The trailer showcases some spectacular effects and action sequences, as well as Gordon-Levitt's subtly altered appearance in order to make him look more like a young Bruce Willis.

Emily Blunt, Jeff Bridges and Paul Dano also star in the film. Bridges appears to be having a career renaissance, with a starring role in Aaron Sorkin's new series The Newsroom and plans to film a Dumb and Dumber sequel with Jim Carrey in the near future.

The concept of time travel is a well-worn cinematic trope and is a tricky sell to audiences who may have grown a little jaded. However, Johnson's unique visual style and the originality of the concept could see the film reach a large audience.

An ageing Willis appears keen to prove to audiences that he is not too old for action. This year he is set to star in The Expendables 2, GI Joe: Retaliation, The Cold Light of Day and has plans to return to his most famous character of John McClane for a fifth Die Hard film.

Looper is due to be released in September.