BB King, a former Mississippi cotton farmer who rose from the Deep South juke joints to become a global blues legend, has died at the age of 89.

The guitarist passed away peacefully in his sleep at his Las Vegas home on Thursday after returning from hospital where he had been treated for high blood pressure and diabetes.

A message posted on his website two weeks ago said: "I am in home hospice care at my residence in Las Vegas. Thanks to all for your well wishes and prayers."

President Barack Obama led tributes to the musician, saying there's "going to be one killer blues session in heaven tonight".

"The blues has lost its king," he said, "and America has lost a legend. No one worked harder than BB. No one inspired more up-and-coming artists."

News of his death triggered shockwaves across social media, with stars from the music world lining up to pay tribute.

King was not only the undisputed king of the blues but a mentor to scores of guitarists including Eric Clapton.

Clapton posted a video tribute on Facebook to the man he called a "dear friend".

He said: "I want to thank him for all the inspiration and encouragement he gave me as a player over the years and the friendship we enjoyed."

Former Beatle Ringo Starr tweeted: "God bless BB King peace and love to his family Ringo and Barbarax."

Rocker Bryan Adams, Dire Straits frontman Mark Knopfler and rapper Snoop Dogg were among a host of others who paid tribute.

King released his first single in 1949 and became known for hits such as Three O'Clock Blues and the 1989 duet When Love Comes to Town with Irish rockers U2.

Born in Mississippi as Riley B King, the musician earned the nickname The King Of Blues and was inducted into the Rock and Roll Hall of Fame in 1987.

King, who was twice married and twice divorced, released 50 albums during his career.

He eked out a subsistence as a sharecropper before going on to sell millions of records worldwide, playing a Gibson guitar he affectionately called Lucille.

King had a deep, resonant singing voice and, despite having what he called "stupid fingers", an immediately recognisable guitar sound.

His unique style of trilling the strings with a fluttering left-hand vibrato, which he called "the butterfly", helped shape early rock.

He delivered stinging single-note licks that brimmed with emotion and were copied by a generation of white rock guitarists.

Only on Monday, a dispute over King's wealth and wellbeing was thrown out of court by a US judge who declared there was no evidence he was being abused.

The ruling in Clark County Family Court kept King's longtime business manager Laverne Toney in legal control of his affairs.

Three of King's 11 surviving children - Karen Williams, Rita Washington and Patty King - suspected Ms Toney of stealing money.

They also accused her of neglecting their father's medical needs, while blocking them from seeing him in home hospice care.

"We lost the battle, but we haven't lost the war," Williams said outside court.