Love letters written by Mick Jagger to a 1960s muse have sold at auction for £187,250.

Sotheby's said a private collector bidding by phone snapped up the Rolling Stones frontman's 10 letters to singer Marsha Hunt.

Marsha is an American-born singer who was the inspiration for the Stones' 1971 hit Brown Sugar and bore Jagger's first child, daughter Karis.

The letters, touching on everything from the moon landing to John Lennon and Yoko Ono, were written in 1969 from the Australian set of Jagger's film Ned Kelly. They had been expected to fetch between £70,000 and £100,000.

Sotheby's books specialist Gabriel Heaton said the letters reveal "a poetic and self-aware 25-year-old with wide-ranging intellectual and artistic interests".

After the sale, Marsha said: "The passage of time has given these letters a place in our cultural history.

"1969 saw the ebbing of a crucial, revolutionary era, highly influenced by such artists as The Beatles, The Rolling Stones, James Brown and Bob Dylan.

"Their inner thoughts should not be the property of only their families, but the public at large, to reveal who these influential artists were - not as commercial images, but their private selves."

Marsha said of the well-preserved letters: "They're addressed to me.

"I was 23, American-born, Berkeley-educated and London-based. Despite his high profile and my own... our delicate love affair remains as much part of his secret history as his concerns over the death of Brian Jones and the suicide attempt of his girlfriend, Marianne Faithfull."