Shia LaBeouf appears naked in a new Sigur Rós music video.

In the graphic music video, Fjögur Píanó, the Transformers star appears nude alongside a blonde woman - dancer Deena Thomsen - but the promo's director Alma Har'el revealed the nudity was not planned, it simply happened spontaneously during the five-day shoot. 

Alma told the Wall Street Journal: "That's the difference between working within a corporate system and something that artistically takes you places you wouldn't expect.

"To me, it's erotic, but it's not selling anything."

The Wall Street Journal describes the video – choreographed by Ryan Heffington – as "more of a dream sequence than a narrative.

"A man and woman go through repetitive motions and get buffeted by two menacing “forces,” bearded guys who feed them glowing candy. LaBeouf’s character, unshaven and with long hair pulled back, trashes a bedroom, weeps and scars his lover. He also dances with her, using jagged, gestural movements."

Watch the video below:

Speaking about the video, Sigur Rós said in a statement: "We don't want to tell anyone how to feel and what to take from it. With the films, we have literally no idea what the directors are going to come back with."

The Icelandic band have given filmmakers the creative freedom to do "whatever comes into their head" when they listen to songs from their sixth studio album Valtari.

Har'el's clip is the third in the series and another is scheduled to appear on the group's website on 2 July.