Mark Ruffalo is appealing to the “greatest fans in the world” with one simple request – not to spoil Avengers: Endgame.

The upcoming Marvel Studios superhero film, directed by the Russo brothers, will bring to an end the story which started in 2008 with Iron Man.

Ruffalo, who plays the Hulk, tweeted a letter penned by the directors which asks fans: “Because so many of you have invested your time, your hearts, and your souls into these stories, we’re once again asking for you help.

“When you see Endgame in the coming weeks, please don’t spoil it for others, the same way you wouldn’t want it spoiled for you.

“Remember, Thanos still demands your silence.”

Although Anthony and Joe avoided giving too much away in the letter, they added they had worked “tirelessly” to deliver an ending which surprises audiences.

“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,” they wrote.

The appeal, which the brothers shared on their own page, is similar to one they tweeted ahead of last year’s instalment in the saga, Infinity War – but has since been deleted.

Robert Downey Jr, who stars as Iron Man, echoed the request at the time, writing on Twitter: “I trust you all can keep a secret.”

Avengers: Endgame is released in UK cinemas on April 25.