Free bassist Andy Fraser has died in California aged 62.

The London-born musician died on March 16 after a long battle with cancer and AIDS, according to an official statement regarding his death.

The Riverside County coroner said the cause of death was not yet known and remains under investigation.

Andy Fraser became a founding member of the British group when he was just 15.

He wrote most of his material with Free lead singer Paul Rodgers, who went on to front bands Bad Company and The Firm.

“A survivor of both cancer and Aids, Andy was a strong social activist and defender of individual human rights,” the statement read.

“He leaves behind his daughters Hannah and Jasmine Fraser, and their mother Ri, his sister Gail, brothers Gavin and Alex, and many friends and associates in the industry.”

Andy Fraser’s All Right Now was Free’s biggest hit, peaking at No 2 in the UK singles chart and No 4 in the US.

All Right Now was recognized by the American Society of Composers, Authors and Publishers in 1990 for achieving over a million radio plays.

In 2006, Andy Fraser and Free singer Paul Rodgers were honored by the BMI in London to mark three million radio and television plays of All Right Now in the UK.

According to an interview with Free drummer Simon Kirke, All Right Now was written “after a bad gig in Durham”.