Muhammad Ali dies: Tributes to legendary boxer

Figures from the world of boxing and beyond have paid tribute to Muhammad Ali, the former world heavyweight boxing champion, who has died aged 74.

"It's a sad day for life, man. I loved Muhammad Ali, he was my friend. Ali will never die. Like Martin Luther King his spirit will live on, he stood for the world.'' - Don King, who promoted many of Ali's fights, including the Rumble in the Jungle

Ali (R) and George Foreman in the Rumble in the Jungle

"Muhammad Ali was one of the greatest human beings I have ever met. No doubt he was one of the best people to have lived in this day and age." - George Foreman, Ali's friend and rival in the Rumble in the Jungle

"His fight outside the ring would cost him his title and his public standing. It would earn him enemies on the left and the right, make him reviled, and nearly send him to jail. But Ali stood his ground. And his victory helped us get used to the America we recognize today." - US President Barack Obama

"Today we bow our heads at the loss of a man who did so much for America. Tomorrow we will raise our heads again remembering that his bravery, his outspokenness, and his sacrifice for the sake of his community and country lives on in the best part of each of us.

"At a time when blacks who spoke up about injustice were labelled uppity and often arrested under one pretext or another, Muhammad willingly sacrificed the best years of his career to stand tall and fight for what he believed was right. In doing so, he made all Americans, black and white, stand taller. I may be 7ft 2in but I never felt taller than when standing in his shadow." - former basketball player Kareem Abdul-Jabbar

"There will never be another Muhammad Ali. The black community all around the world, black people all around the world, needed him. He was the voice for us. He's the voice for me to be where I'm at today." - Floyd Mayweather, world champion boxer across five divisions

"Everybody wanted to box because of him. He was just so amazing in every way. More than anything else it was how humble and how brilliantly charismatic he was. He was a beautiful-looking man, a beautiful-looking individual and he had so much compassion. He was the greatest sportsman there has ever been and we were very lucky that he chose boxing." - Barry McGuigan, former world featherweight champion

"You were a champion in so many ways. You 'fought' well. Rest well." - Bernice King, daughter of civil rights leader Martin Luther King

The 22-year-old Cassius Clay upset Sonny Liston to win the world heavyweight title in February 1964

"We lost a giant today. Boxing benefitted from Muhammad Ali's talents but not as much as mankind benefitted from his humanity." - Filipino world champion across six divisions, Manny Pacquiao

"The values of hard work, conviction and compassion that Muhammad Ali developed while growing up in Louisville helped him become a global icon. As a boxer, he became The Greatest, though his most lasting victories happened outside the ring." - Greg Fischer, mayor of Louisville, Kentucky

"Ali, he was and always will be the greatest. A true champion in and out of the ring...

"He stood for something and by standing for something he made us stronger and he made us better...

"Real champions fight until they can't fight no more, and then fight anyhow." - civil rights leader Reverend Al Sharpton

"He was the greatest fighter of all time but his boxing career is secondary to his contribution to the world. He's the most transforming figure of my time certainly. He did more to change race relations and the views of people than even Martin Luther King." - boxing promoter Bob Arum

"Ali, the G-O-A-T [Greatest Of All Time]. A giant, an inspiration, a man of peace, a warrior for the cure. Thank you." - US actor and fellow Parkinson's battler Michael J Fox

President Clinton awarded Ali the Presidential Citizens Medal in 2001

"Hillary and I are saddened by the passing of Muhammad Ali. From the day he claimed the Olympic gold medal in 1960, boxing fans across the world knew they were seeing a blend of beauty and grace, speed and strength that may never be matched again.

"We watched him grow from the brash self-confidence of youth and success into a manhood full of religious and political convictions that led him to make tough choices and live with the consequences.

"Along the way we saw him courageous in the ring, inspiring to the young, compassionate to those in need, and strong and good-humoured in bearing the burden of his own health challenges." Former US President Bill Clinton, and husband of Democratic frontrunner Hillary Clinton

"Muhammad Ali was the greatest, not only an extraordinary athlete but a man of great courage and humanity." - Democratic presidential candidate Bernie Sanders

"Muhammad Ali is dead at 74! A truly great champion and a wonderful guy. He will be missed by all!" - Republican presumptive presidential nominee Donald Trump on Twitter

"With an incomparable combination of principle, charm, wit and grace, he fought for a better world and used his platform to help lift up humanity." - spokesman for U.N. Secretary-General Ban Ki-moon

"Muhammad Ali was not just a champion in the ring - he was a champion of civil rights, and a role model for so many people." - British Prime Minister David Cameron