Speculation has spread on social media that Marvel's next Avengers movie is being secretly filmed at England's historic Durham Cathedral.

The 900 year-old Durham Cathedral will be closed for several days next week, while the site is currently reported to be surrounded by filming equipment, green screens and security teams.

Many are speculating that the 'major project' causing the Cathedral's closure on May 4-6, and Tuesday May 9, is the production of Avengers: Infinity War, the hotly anticipated, big budget superhero sequel from Marvel Studios.

Approached by Christian Today for comment on the upcoming closure, Durham Cathedral said: 'It's a major event, we don't know anything about it.'

A March tweet featuring the film's directors Joe and Anthony Russo, location scouting in what was believed to be Durham, sparked the rumours. It has since been deleted, according to Durham Magazine.

None of the movies' stars have been spotted in the area yet. One paper, exploring Durham's Palace Green and the cathedral surroundings, were reportedly told by the project's 'head of security' to delete any photos of filming equipment.

The security head told The Tab that the production was for 'the installation of a penthouse suite at the top of the tower for the Dean and his wife, because they want to be closer to God'.

He reportedly added that 'They're also having an ice rink put in', and said the green screens – used commonly in films for visualising special effects – were present 'because they don't want to look at the walls'. He's believed to have been joking. 

Durham Cathedral, a UNESCO World Heritage Site, recently voted 'Britain's favourite cathedral', is no stranger to big-budget film productions. Its ancient cloisters and towers were used in the Harry Potter films as the location for Hogwarts School of Witchcraft and Wizardry.

England's Gloucester Cathedral was also used as an interior for Harry Potter, as well as the BBC's Sherlock, while Lincoln Cathedral has been used for films such as Young Victoria and The Da Vinci Code.

Avengers: Infinity War has recently been filming not far from Durham, on location in and around Edinburgh, Scotland.

The May 2018 film is set to be the comic-book franchise's biggest yet, the first volume of a two-part epic concluding 'Phase Three' of the evolving Marvel Cinematic Universe. Its stars include Scarlett Johansson, Tom Hiddleston, Robert Downey Jr, Benedict Cumberbatch, Chris Pratt, Zoe Saldana, Samuel L Jackson and Chris Hemsworth.