Tom Holland can't keep a secret.

The 21-year-old actor will reprise the role of Spider-Man to star alongside the likes of Robert Downey Jr., Chris Hemsworth and Mark Ruffalo in 'Avengers: Infinity War' in 2018 - but Marvel has kept Tom in the dark about the plot because he can't keep his mouth shut.

Tom - whose first standalone Marvel movie, 'Spider-Man: Homecoming', will be released in cinemas next month - said: ''I don't know anything about it or what it's about.

''I know who the villain is, but that's it. They don't let me read anything because I'm so bad at keeping secrets.''

But Tom insisted the 'Avengers' movie doesn't need any additional hype, saying it will be the ''biggest movie of all time''.

He told the Toronto Sun newspaper: '''Infinity War' needs no teasing.

''That movie literally needs no teasing. It's going to be the biggest movie of all time. Believe me; no one is ready for this movie.''

Meanwhile, Tom recently revealed he got in trouble with police for throwing signed pictures at his fans.

The actor was told he couldn't meet the loyal supporters who were waiting outside his hotel because he didn't have time to leave the building between interviews.

So in order to make them feel appreciated, Tom began signing pages from 'Spider-Man' comics and throwing them down to the assembled group.

He recalled: ''The thing is, we weren't allowed to leave the hotel because of timing issues, we had to get right to an interview.

''So our way of, like, sending the fans things was scrunching up signed pictures and throwing them out the window.

''Admittedly, the police got really mad at one point and were like, 'Stop throwing pictures!' But yeah, we got as many out as we could.''