Will Smith, David Beckham and Spike Lee were among the huge crowds who turned out to pay their respects for the late, great Muhammad Ali at a memorial service in his home town of Louisville, Kentucky.

Tens of thousands of fans lined the streets, chanting “Ali! Ali!” as the hearse travelled 19 miles through Loiusville to honour the boxing great.

Famous mourners at Muhammad Ali's funeralDavid Beckham (David Goldman/PA)

The casket, covered in a cloth bearing Arabic writing, was placed into the hearse by pallbearers, who included Hollywood star Will Smith and former boxers Lennox Lewis and Mike Tyson, before it left the funeral home.

The procession then travelled along Muhammad Ali Boulevard, passing the Muhammad Ali Centre and his childhood home as fans threw flowers towards the vehicle carrying Ali’s body.

As huge crowds waited in sweltering heat for the procession to pass, some of Ali’s family and friends in the cars following the hearse waved to people watching from the roadside.

Famous mourners at Muhammad Ali's funeralWill Smith (David Goldman/PA)

US president Barack Obama, who missed the funeral to attend his daughter Malia’s high school graduation ceremony, described Ali as “an icon” and a “personal hero” who transformed “not just the world of sport, but the world as a whole”.

Famous mourners at Muhammad Ali's funeralNBA executive Pat Riley (David Goldman/PA)

In a video message, Obama said: “It’s very rare when a figure captures the imagination of the entire world. It’s even rarer when that figure does so by being open and funny and generous and courageous.

“He was one of a kind. In my book, he’ll always be the greatest.”

Obama and his wife Michelle sent a letter to be read at the service, where White House senior adviser Valerie Jarrett – who knew Ali personally – represented the president.

Famous mourners at Muhammad Ali's funeralFormer Governor of California Arnold Schwarzenegger (David Goldman/PA)

Murad Qureshi said he and and his brother-in-law Adam Shabbir made the 4,000-mile trip from London to pay respects to “The Greatest”.

He told the Press Association: “I remember when my father passed away, I said the only other funeral I would want to be at would be Muhammad Ali’s one.

“Very simply, he’s the greatest. He’s had a phenomenal influence on a lot of our lives – not just in the sporting arena as the world heavyweight champion three times, but also as a civil rights campaigner and a conscientious objector.”

Famous mourners at Muhammad Ali's funeralSpike Lee, left, speaks to Former President of Afghanistan Hamid Karzai (David Goldman/PA)

Up to 18,000 people attended the huge public memorial at the KFC Yum! Centre, with the ceremony broadcast to millions of viewers around the world.

Former US president Bill Clinton was delivering the eulogy, while Ali’s widow Lonnie and two of his nine children, daughters Rasheda and Maryum, were addressing the congregation.

Famous mourners at Muhammad Ali's funeralLennox Lewis (David Goldman/PA)

The pallbearers included Jerry Ellis – the brother of Jimmy Ellis, Ali’s former sparring partner and fellow world heavyweight champion – and Ali’s cousins John Grady and Jan Wadell, nephew Ibn Ali, former brother-in-law Komawi Ali and family friend John Ramsey.

The funeral was live-streamed on the internet as well as being shown at London’s 02 Arena, the site of his I Am The Greatest Exhibition.

Mourners on the streets(Mark Humphrey/AP)

Some ticket-holders for the funeral have been criticised for trying to profit from the free event by selling tickets online.

Ali family spokesman Bob Gunnell said he was “personally disgusted” at attempts to profit from Ali’s funeral and urged people not to buy the tickets.

A traditional Islamic prayer service was held for Ali on Thursday at Freedom Hall, where Ali made his professional debut with victory over Tunney Hunsaker in 1960.