An emotional Mr Zuma broke the news to the nation during a live press conference that began about 8.45am AEDT.

"Our thoughts and prayers are with the Mandela family," he said.

"To them we owe a debt of gratitude. They have sacrificed much and endured much so that our people could be free.

"Our thoughts are with the millions of people across the world who embraced him.

"This is the moment of our deepest sorrow, our nation has lost its greatest son."

Mandela, the country's first black president, died peacefully at his Johannesburg home after a prolonged lung infection.

The anti-apartheid icon, known in South Africa by his clan name of Madiba, emerged from 27 years in apartheid prisons to help guide South Africa through bloodshed and turmoil to democracy.

In a nationally televised address, Mr Zuma said Mandela would have a full state funeral. He ordered flags to be flown at half mast until then.

"Fellow South Africans, our beloved Nelson Rohlihla Mandela, the founding president of our democratic nation, has departed," Mr Zuma said.

"He passed on peacefully in the comfort of his home."

Mr Zuma called for South Africans to unite and to farewell Mandela in a manner fitting of his legacy.

"Fellow South Africans, Nelson Mandela brought us together and it is together that we will bid him farewell.

"As we gather to pay our last respect, let us conduct ourselves with the dignity and respect that Madiba personified.

"Be mindful of his wishes and the wishes of his children.

"May his soul rest in peace, God Bless South Africa."

Mandela rose from rural obscurity to challenge the might of white minority apartheid government - a struggle that gave the 20th century one of its most respected and loved figures.

He was among the first to advocate armed resistance to apartheid in 1960, but was quick to preach reconciliation and forgiveness when the country's white minority began easing its grip on power 30 years later.

Mandela, imprisoned for nearly three decades, was elected president in landmark all-race elections in 1994 and retired in 1999.

He was awarded the Nobel Peace Prize in 1993, an honour he shared with F.W. de Klerk, the white Afrikaner leader who released from jail arguably the world's most famous political prisoner.

 As president, Mandela faced the monumental task of forging a new nation from the deep racial injustices left over from the apartheid era, making reconciliation the theme of his time in office.

The hallmark of Mandela's mission was the Truth and Reconciliation Commission which probed apartheid crimes on both sides of the struggle and tried to heal the country's wounds. It also provided a model for other countries torn by civil strife.

In 1999, Mandela handed over power to younger leaders better equipped to manage a modern economy - a rare voluntary departure from power cited as an example to African leaders.

In retirement, he shifted his energies to battling South Africa's AIDS crisis and the struggle became personal when he lost his only surviving son to the disease in 2005.

Mandela's last major appearance on the global stage came in 2010 when he attended the championship match of the soccer World Cup, where he received a thunderous ovation from the 90,000 at the stadium in Soweto, the neighbourhood in which he cut his teeth as a resistance leader.

Charged with capital offences in the infamous 1963 Rivonia Trial, his statement from the dock was his political testimony.

"During my lifetime I have dedicated myself to this struggle of the African people. I have fought against white domination, and I have fought against black domination.

SMH.COM.AU