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The world's longest piece of music is being performed live for the first time on a unique 20-metre-wide instrument at a concert at The Roundhouse in London.

The Longplayer is a 1,000-year-long composition by Jem Finer and is played out by computer at several public listening posts around the world.

It began playing on 31 December 1999 and will continue - without repetition - until the last moment of 2999.

The live performance will play a 1,000 minute section of the music.

The performance began on Saturday morning and continue until the early hours of Sunday morning.

It was in 2002 that Finer - who was also one of the founding members of pop group The Pogues - developed a score for the music.

It allows the piece to be played as an orchestral installation comprising of six concentric rings of Tibetan singing bowls.

It is this arrangement that is being performed at the Roundhouse concert.

The Longplayer is continually played out at its flagship location, the Lighthouse in Trinity Buoy Wharf in London, but listening posts are also stationed in Australia, Egypt and the US.