The star was among a long list of celebrity guests at the public interfaith funeral, which was held at the KFC Yum! Center in Ali's native Louisville, Kentucky, where an estimated 15,000 fans, friends and relatives gathered to remember the icon.

The near three-hour-long memorial concluded a day of celebrations for Ali, who took one last ride through his beloved city in a funeral procession, which passed through his childhood neighbourhood en route to the Cave Hill Cemetery, where he was laid to rest in a private ceremony.

Pallbearers included Will Smith, and former boxing stars Mike Tyson and Lennox Lewis, while Billy Crystal and former U.S. President Bill Clinton read eulogies at the service.

Schwarzenegger said the boxing champion was his close friend and idol, and paid a touching tribute to the sports star who dubbed himself The Greatest Of All Time. "I just came here to honour Ali, because I think he was a great motivation for all of us, and he was an idol of mine," he told Entertainment Tonight on Friday.

"People ask me, 'Who are some of your idols?' He's one of the five people that I always mention, because of his generosity and because of his great skills."

The star also explained that while he admired Ali for his sporting prowess, he also looked up to him because of his philanthropy. "I've seen him first-hand handing out $100 bills," he said of the boxing icon. "He was just a great friend that I had a lot of fun hanging out with."

The unlikely pair met in TV studios across America during the 1970s, when Schwarzenegger was promoting the 1977 docudrama Pumping Iron, and Ali was promoting his fights.

"We were going around the country promoting and then always having a great time and great laugh. Then we promoted some charities together. So I just love the guy. I think he was fantastic!" he recalled.

The three-time world heavyweight champion, who battled Parkinson's disease for 32 years, died from septic shock in Phoenix, Arizona on 3 June (16).