Former president Thabo Mbeki spoke firmly on Sunday evening about the importance of strong leadership and honouring South Africa's Constitution, in his first public address since Nelson Mandela passed away.

"Do we have the quality of leadership such as was exemplified by Nelson Mandela and others sufficient to respond to the challenges we face?" asked Mbeki who repeatedly warned against betraying Mandela's legacy and values.

Mbeki said South Africa had rightly been asked to celebrate Mandela's life instead of just mourning. "But I don't think we should end there, we must also ask ourselves a question: What about the future? I think as we celebrate the life of Nelson Mandela, this becomes a central task: to ensure we do not betray what he and others sacrificed for."

Mbeki's words come at a difficult time in South African politics and governance.

Mbeki was successor to Mandela, South Africa's first democratically elected president. He was ousted as president of the ANC by South Africa's current president, Jacob Zuma in a bruising succession battle. Zuma's term in office and prior years have been plagued by scandal, both personal and political, and policy indecision. Allegations of government misspending on his personal residence in Nkandla to the tune of a reported R200-million have further damaged his image. 

Mbeki too had a mixed time in office, marked by Aids denialism but there has been nostalgia in some quarters for his strong policy direction and leadership. 

"The task of managing the transition of South Africa is a very difficult task, I think in many respects more difficult than the struggle to end the system of apartheid," he said, in one of many remarks that seemed directed straight at the country's current leadership.

Mbeki was speaking at the historical Oxford Synagogue in Killarney, Johannesburg, as part of a series of appearances by ANC leaders at places of worship for the nationally declared day of prayer and reflection.

Wearing a dark suit and a yarmulke, a traditional Jewish cap, Mbeki first paid homage to black and white South Africans who had helped end apartheid. 

"We were inspired as young people what he and his generation were able to do, to engage in struggle, to end the injustice of apartheid," he said. "We were inspired by many leaders, we never asked questions about their colour and race."

But Mbeki did not dwell on the contribution of key South African Jewish figures in the struggle against apartheid, instead zoning in on the importance of leadership and the Constitution. 

One of the key outcomes of the struggle was the country's Constitution, said Mbeki. "The national Constitution bears the very heavy imprint of the vision and the values which Nelson Mandela and his generation stood for."

The country's Constitution, though celebrated as one of the world's most progressive documents of its kind, has come under attack from more radical sectors, both within and outside the ANC, that see it as a product of compromise by the outgoing white apartheid government, which stifles economic freedom for the black majority in South Africa. 

The newly established Economic Freedom Fighters, formed by ousted ANC Youth League president Julius Malema, is campaigning for next year's elections on a platform of radical legislative change, including mine nationalisations and land grabs.

Leaders within the ANC have also hinted at the need to change the Constitution.

But on Sunday Mbeki was more concerned with giving life to the document and achieving its stated aims. 

"Twenty years into democracy, how far are we with regards to the goal of creating a non-racial society, of achieving national reconciliation, of creating a non-sexist South Africa, a prosperous South Africa ... of a shared wealth among our people and eradication of poverty?" he asked.

"What did we do in the past with regards to all these matters and what should we do next to accelerate progress to the goals of all these things contained in our Constitution."

Mbeki related a personal story of meeting the chief counsel of the Rivonia trialists, the late Bram Fischer, after the arrested ANC leaders were sentenced and Mandela began his 27-year imprisonment. 

"Bram said he had a difficult battle with the Rivonia trialists, because they told him if they were sentenced to death he should not appeal. Their argument was if they were, the people of South Africa would act to ensure that the death sentence was not executed. Such was their confidence in all of us," said Mbeki.

"They said it would not be right to depend on the mercy of an apartheid judiciary, but rather rely on the conscience of the people of South Africa."

The synagogue's prayers and service continued after a number of other leaders spoke, including an impassioned speech from Chief Rabbi Warren Goldstein, relating key stories from Nelson Mandela's autobiography and likening him to the biblical figure of Joseph, who was sent to prison though innocent and later became great.

Israel's ambassador to South Africa Arthur Lenk also spoke briefly, skirting delicately the issue of Mandela's difficult relationship with Israel and identification with the people of Palestine. 

The synagogue was packed to capacity with people standing in the aisles and outside the auditorium, craning to hear Mbeki.

In closing, the former president quoted Mandela's famous words from the dock, that he was willing to die for his ideals, and urged for greater commitment to principles in South Africa. 

"What do we do to ensure this noble legacy Nelson Mandela and others left behind not be betrayed?" he asked.