Obama says Ali 'shook up the world'

US President Barack Obama says Muhammad Ali "shook up the world and the world is better for it."

The death of the three-time world heavyweight boxing champion Muhammad Ali was confirmed in a statement issued by family spokesman Bob Gunnell late on Friday evening, a day after the 74-year-old was admitted to a Phoenix-area hospital with a respiratory ailment.

Obama said in a statement on Saturday he kept a pair of Ali's gloves on display in his private study, just off the Oval Office and under the famous photograph of the young champion "roaring like a lion over fallen Sonny Listen."

Ali "fought for what was right," stood with Martin Luther King Jr. and Nelson Mandela "when it was hard" and "spoke out when others wouldn't," Obame said

He said that even as Ali's physical powers were in decline, the boxing great "became an even more powerful force for peace and reconciliation around the world."

The president said Parkinson's disease may have "ravaged" Ali's body, but it "couldn't take the spark from his eyes."