The keyboard player in the 70s progressive 'prog-rock' supergroup Emerson, Lake & Palmer has died at the age of 71.

Keith Emerson died on Thursday at his home in Santa Monica, California, according to a post on the band's Facebook page.

The cause of death was not announced.

Friends are describing him as a gentle soul, a pioneer and an innovator.

The English band released nine studio albums during the 1970s - Mr Emerson discovering the Moog Synthesiser and the Theremin as a teenager.

Emerson later worked as a solo artist and wrote an autobiography, Pictures of an Exhibitionist, in 2004.