Avengers: Endgame directors Anthony and Joe Russo are urging fans who catch early screenings to keep spoilers under wraps.

The filmmaking brothers are gearing up to release the feature, based on the superhero team depicted in Marvel Comics, around the world from 24 April (19).

However, after some footage from the movie leaked online earlier this week, Anthony and Joe have taken to Twitter to share a letter in which they beg viewers to keep details under wraps until the final instalment of the Avengers series officially opens in cinemas.

"To the greatest fans in the world," they begin. "This is it. This is the end. The end of an unprecedented narrative mosaic spanning eleven years and eleven franchises.

"For all of you who have been on this journey with us since the very beginning, sharing every high and low with your family, your friends, your classmates, your co-workers. Investing so deeply in every character and storyline. Laughing. Cheering. Shedding tears. Giving so freely of your thoughts and emotions in spirited dialogue, theories, fan art, and fan fiction. Please know that the two of us, along with everyone involved in Endgame, have worked tirelessly for the last three years with the sole intention of delivering a surprising and emotionally powerful conclusion to the Infinity Saga."

Anthony and Joe added that they are thankful that so many people have invested their time, hearts and souls into the stories, and sincerely wish that audiences won't spoil the ending for others, "the same way you wouldn't want it spoiled for you".

To conclude their letter, the duo commented: "Remember, Thanos still demands your silence. As always, good luck and happy viewing... The Russo Brothers #DontSpoilTheEndgame."

Avengers: Endgame is the 22nd film in the Marvel Cinematic Universe and features an ensemble cast including Robert Downey Jr., Chris Evans, Mark Ruffalo, Chris Hemsworth, and Scarlett Johansson.