The body of legendary boxer Muhammad Ali on Sunday arrived in his hometown Louisville in Kentucky where a public procession and memorial service will be held on Friday.

The memorial service of Ali, born Cassius Marcellus Clay, will be followed by a private funeral where former US president Bill Clinton will participate, Efe news reported.

"Ali is now home," said Louisville Mayor Greg Fischer.

Ali died on Friday night at the age of 74 at a hospital in Arizona where he spent the last years of his life because the weather was more suitable for him as he was suffering from Parkinson's disease.

Family and close friends will bid farewell to the legend in a private ceremony on Thursday in Louisville, said family spokesman Bob Gunnel on Saturday.

On Friday, a procession bearing the body of the triple world boxing champion will be marched through the streets of Louisville, first around the museum and cultural centre of Ali and later through the boulevard that bears his name and then to the Cave Hill cemetery.

The burial ceremony will be private with the sole participation of his family, former US President Bill Clinton, comedian Billy Crystal and journalist Bryant Gumbel, the spokesman detailed.

On Saturday, Louisville Mayor ordered that American flags be flown at half-mast at all government buildings in the city until Ali is buried.

The importance of Muhammad Ali goes beyond boxing and embeds itself in the turbulent times in the 1960s, during the African-American Civil Rights Movement, when the boxer refused military service in Vietnam and called for the equality of all people regardless of religion, social status and skin colour.

Ali converted to Islam and was a member of the religious organisation the 'Nation of Islam', like Malcolm X, symbol of the most radical civil rights movement in the 60s.

According to Ali's beliefs, his burial will be led by an imam and conducted under Muslim rites.