Chris Pratt: The aliens in 'The Tomorrow War' are scarier than Thanos (exclusive)

Watch: The Tomorrow War cast discuss the film's terrifying alien beasts

Chris Pratt says the aliens he's forced to fight in The Tomorrow War are "the most terrifying aliens I've ever seen on screen" — even compared to the likes of Thanos.

In the new blockbuster, Pratt plays science teacher and former military man Dan Forester, who is drafted to travel forward in time in order to fight aliens trying to wipe out the human race.

The monsters are gargantuan foes, boasting mammoth size and flailing tentacles, with dozens of ways to kill off a person.

Read more: Pratt hypes up MCU return in Thor: Love And Thunder

When asked how the film's aliens compared with the dinosaurs Pratt has squared up against in the Jurassic World franchise and the intergalactic baddies of the Marvel Cinematic Universe, he tells Yahoo Entertainment UK they could match any of them.

"I think, not only in the films that I've been a part of, but from any film I've ever seen, I think they're the most terrifying alien I've ever seen on screen," he says.

Pratt adds: "They're incredible. They are not necessarily intelligent. They're just massive, hungry beasts that are super-deadly, planet-clearing, flesh-eating monsters.

"There's no nuance. They're not here to try to understand our way of being. They just want to eat us. And that was pretty scary."

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The creatures, like many of Pratt's other adversaries, are realised via expensive-looking CGI, but co-star Yvonne Strahovski says there was plenty to be scared of on set too.

"The previz put together videos of what it would look like and art. There was a prosthetic version of it on set as well," she says.

"I love the aspect of the alien that is so unpredictable. It's very erratic and that to me was the scariest part. You really couldn't predict what it was going to do or where it was going to go next. They were just these feasting, crazy animalistic kind of beasts that are terrifying."

Even the leading lights of the human resistance against the alien threat couldn't stop themselves from being terrified by what they saw in the finished movie.

"I'm glad I didn't know how scary they were actually going to be while I was filming it, because I probably wouldn't have played it as cool," says Jasmine Mathews, who plays Lieutenant Hart in the movie.

Read more: Pratt compares Jurassic World: Dominion to Avengers: Endgame

Keith Powers, who portrays Major Greenwood, agrees with his co-star's assessment, saying: "When the reveal happened, it still looked different to what we were seeing on set. I was like: this is crazy and it was a little frightening.

"When I was seeing the storyboards and stuff, I was like this going to be crazy and this is amazing."

The Tomorrow War is available to stream via Amazon Prime Video from 2 July.

Watch: Trailer for The Tomorrow War