Radiohead rocker Thom Yorke has recorded a song that last a whopping 18 DAYS - around 400 times longer than the world's official longest song.

The British musician wrote 'Subterranea' - which lasts 432 hours - to cover every second of an 18-day art exhibition by Stanley Donwood, who oesigned all of Radiohead's artwork and album covers.

The track is made up of 25,290 minutes of experimental sounds and recordings, which were created especially for the show which is currently open in Sydney's Carriageworks centre until June 6.

Radiohead frontman Thom Yorke, pictured above performing at Glastonbury, has recorded a track lasting 18 days for an art exhibition by a designer who created most of the group's artwork and album covers

Stanley Donwood designed all of Yorke's (left) band's album covers, including hit release OK Computer (right)

Promoters promise that 'no minute [of music] is the same over 18 days' - but revealed it will not be released after the exhibition is finished.

The track is currently being being blasted out over three levels of speaker systems, and an exhibition spokesman said: 'subs will boom from the floor, mids will echo through the walls while the highs rain down from the ceiling', reports Triple J music website.

The track is around 400 times longer that 'The Scriptures;, which holds the official Guinness world record for the longest ever recorded song.

Written by the Love Hope Strength Foundation and released in 2014, it lasts one hour, 43 minutes and 40 seconds, has 75 verses and features more than 200 contributors.