PILTON, England: An official in Britain's ruling Conservative Party and friend of prime minister David Cameron has died at the Glastonbury music festival in southwest England, the festival's founder Michael Eavis said on Sunday.

Cameron paid tribute to Christopher Shale, chairman of the Conservative Association in Cameron's own West Oxfordshire constituency and a friend of Cameron and his wife Samantha.

“Sam and I were devastated to hear the news about Christopher,” he said in a statement. “He was a great friend and has been a huge support over the last decade in west Oxfordshire. A big rock in my life has suddenly been rolled away.”

Shale was found dead in a portable toilet in a backstage area where upmarket accommodation is located, close to the main press tent, on Sunday morning, the last day of the Glastonbury music festival which is held most years on Eavis's Worthy Farm.

Inspector Chris Morgan of Avon and Somerset Police said investigators were still trying to establish the cause of death.

It was being treated as “unexplained”, and a post mortem was due to take place later on Sunday.

Eavis told reporters that while the cause of death was not confirmed, he understood it to be a suicide. However, police sources said there was nothing to suggest at this stage that suicide was the cause.