The process, which uses water instead of fire, is considered to be a more environmentally friendly alternative to cremation.

Hot water is combined with potassium hydroxide or sodium hydroxide to break down body tissue, with the person's bones placed in a cremulator and turned to ash.

Desmond Tutu: The South African icon who was loved far and beyond his native land

President Cyril Ramaphosa is expected to deliver the main eulogy at the service at St George's Chapel in Cape Town.

Desmond Tutu's body had been lying-in-state in the cathedral where he preached against racial injustice.

Hundreds of mourners stood in long queues on Thursday and Friday, some singing, others carrying flowers and writing on tribute books in memory of the Nobel Peace Prize winner.

Tutu, who was South Africa's first black archbishop, requested "no lavish spending" on his funeral and he even "asked that the coffin be the cheapest available", his foundation said.

The archbishop is widely revered across racial and cultural divides in South Africa for his moral rectitude and principled fight against white-minority rule.

He died aged 90 on 26 December.

His death represents a huge loss for South Africa, where many called him "Tata" - meaning father.

Church bells have been rung every day in his honour since his death and tributes and prayers have poured in from around the world.

Tutu won the Nobel Peace Prize in 1984 in recognition of his non-violent opposition to South Africa's apartheid regime.

A decade later, he witnessed the end of that regime and chaired a Truth and Reconciliation Commission to help unearth state-sponsored atrocities during that era.