British four piece Alt-J have announced that one of the founding members, Gwil Sainsbury, has left the band.

The group made the announcement about the guitar and bass player on Twitter.

The post said: "With regret, Gwil is leaving Alt-J. This is purely a personal decision and as our best friend we support him completely."

In 2012 they won the Mercury Prize for their critically-acclaimed album An Awesome Wave.

The band formed in 2007 after meeting at university in Leeds.

Last year they performed at festivals across the UK, including Glastonbury, Radio 1's Big Weekend and Reading and Leeds.

Many followers on Twitter have expressed their shock and sadness at the decision.

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