Marvel's latest superhero flick Thor: Ragnarok is "furiously" circulating on illicit pirate and streaming services – seemingly after being leaked online by mistake.

According to TorrentFreak, a now-deleted Reddit thread claimed that a legal pre-order of the film was made available for early download in error. The hollywood blockbuster – the latest in Marvel's 'The Avengers' franchise – is currently set for digital release on 19 February.

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The Reddit post stated: "I pre-ordered Thor: Ragnarok on Vudu yesterday and it links it to my iTunes also.

"But curiously it showed up in my iTunes library this morning (pre-orders shouldn't). And now I can watch the full movie in HD. I obviously downloaded it."

The user had an account on MoviesAnywhere – tied to both Vudu and iTunes – and soon other Reddit users were commenting they had also accessed the movie. It remains unclear how it came to be available.

"Due to what appears to be a significant blunder at Apple, the $180 million movie is now being furiously pirated all over the internet," TorrentFreak wrote Monday (22 January).

It wasn't long after appearing on the web that a well-known pirate group – dubbed "Evo" – set to work on making the movie available on peer-to-peer websites like The Pirate Bay. In a statement, the team revealed that it took "more than 10 hours" to break iTunes' protection.

It wrote (mirrored on PasteBin): "Casualties: 1 account banned. Lol. But it was worth it. Enjoy fellas. Have a good weekend. No VIP required. No pennies needed. All free."

A quick search on The Pirate Bay by IBTimes UK confirmed that numerous copies of Thor: Ragnarok were in circulation online. It is illegal to download copyrighted material in the UK.

In May 2016, it was confirmed that online pirates could face up to 10 years in prison under harsher anti-piracy laws. The legislation – called the Digital Economy Act – came into effect last year.

Both Marvel and Disney Studios did not immediately respond to a request for comment. In previous cases, film studios have attempted to prosecute those who access movies before official release.