Archbishop Desmond Tutu has led a special service in Cape Town today in memory of his close friend, the late Nelson Mandela.

The service at St George's Cathedral was also joined by the current Archbishop of Cape Town, Thabo Makgoba.

Flags are flying at half mast across South Africa in honour of the nation's first black president, who passed away on Thursday evening at the age of 95 after a long period of ill health.

During the prayer service at St George's Cathedral, Archbishop Tutu appealed to South Africans to adhere to Mandela's values of "unity and democracy".

"God, thank you for the gift of Madiba," he said.

Speaking to the media later in the day, Archbishop Tutu asked: "What's going to happen to us? Now that our father has died?

"Some have suggested that after he is gone, as he is gone, our country is going to go up in flames - this is I think to discredit us, South Africans, to discredit his legacy."

The Archbishop said South Africa had "amazed the world" because of Mandela and the end he brought to apartheid.

"The sun will rise tomorrow. It will not be as bright as yesterday. But life will carry on," he said.

"God is asking South Africans, please become what you are, show the world we are members of one family. We belong together."

South Africa is marking 10 days of mourning before Mandela's state funeral is held in Quino, the village where he grew up, on December 15.

Before that, on December 10, tens of thousands of people are expected to attend a memorial service at Cape Town's FNB Stadium, where Mandela made his last public appearance at the closing ceremony of the 2010 World Cup.