LONDON (AFP) - British rock musician Greg Lake, singer with 1970s progressive rock groups King Crimson and Emerson, Lake & Palmer, has died of cancer aged 69, his manager announced on Thursday (Dec 8).

"Yesterday, December 7, I lost my best friend to a long and stubborn battle with cancer," Stewart Young wrote on the musician's official website.

"Greg Lake will stay in my heart forever, as he has always been," he added.

Lake was a founder member and frontman of seminal progressive rock group King Crimson, who scored a worldwide hit with 1969 album In The Court Of The Crimson King.

He later struck up a friendship with fellow "prog-rocker" Keith Emerson and the pair recruited Carl Palmer to form supergroup Emerson, Lake & Palmer in 1970.

The band sold more than 48 million records, incorporating classical music and virtuoso musicianship into the rock canon, with heavy metal bands such as Iron Maiden citing them as an influence.

"As Greg sang at the end of Pictures At An Exhibition, 'death is life'," said former bandmate Palmer.

"His music can now live forever in the hearts of all who loved him."

Emerson committed suicide earlier this year in Los Angeles.

Lake also had solo hits, including Christmas single I Believe In Father Christmas, which reached number two in the British charts in 1975.

Yes keyboardist Rick Wakeman paid tribute on Twitter, writing: "Another sad loss with the passing of Greg Lake... You left some great music with us my friend & so like Keith, you will live on."