Avengers Age of Ultron: Third trailer released after fans 'unlock' video on Twitter

The video was released following a Twitter contest

Marvel's latest poster for its forthcoming movie Avengers: Age of Ultron

Marvel Studios has released the dramatic third trailer for its upcoming film Avengers: Age of Ultron.

The action-packed trailer was unveiled following a Twitter contest, which saw fans tweeting #AvengersAssemble to unlock the footage.

It shows villain Ultron ominously pledge to steal people's hope in his bid to exterminate humanity.

Fans are also given a glimpse Paul Bettany as Vision - an android created by Ultron which joins forces with the Avengers.

The star-studded film will feature Robert Downey Jr., as Iron Man, Scarlett Johansson as Black Widow, Chris Evans as Captain America, Chris Hemsworth as Thor, Mark Ruffalo as The Hulk and Jeremy Renner as Hawkeye.

Avengers: Age of Ultron will follow the team's attempt to defeat James Spader as Ultron, and stop him from enacting his terrible plans.