It was due to air in the US this Tuesday on the ABC network.
According to reports, a low-res version of the trailer found its way online. The original source is still not known.
Marvel tweeted about the leak, using humor to blame it on Hydra, a reference to the fictional terrorist organisation from Marvel comic books. It then decided to post the full HD trailer on YouTube:
In Avengers: Age of Ultron, the Avengers need to work together to defeat Ultron, a self-aware artificial intelligence which sees humans as the main enemy and sets to eradicate them from earth.
The movie reunites Scarlett Johanassen as Black Widow, Robert Downey Jnr as Iron man, Chris Hemsworth as Thor, Mark Ruffalo as the Hulk, Chris Evans as Captain America and Jeremy Renner as Hawkeye.
It will introduce two new characters. Aaron Taylor-Johnson will star as Quicksilver and Elizabeth Olsen as the Scarlet Witch.
Avengers: Age of Ultron hits Malaysian cinemas on April 30, 2015.
