Mandela keeps his opinions to himself as a nation marks its idol's birthday

After bitter rows with his successor, the former South African president has fallen silent on political issues
He still attends public events and lends his name to numerous causes but when it comes to politics Nelson Mandela, perhaps the world's most powerful moral voice, has fallen silent.

South Africa is celebrating his 88th birthday today in a blaze of affection, but in ignorance of the former president's views on key national and international questions. The silence follows bitter clashes with his successor, Thabo Mbeki, when Mr Mandela was told to stop interfering in government policy.

"Mandela was treated like a difficult and bothersome old man who should go away," said Mark Gevisser, author of an upcoming biography of President Mbeki. "It's possible he threw up his hands and concluded his moment had come and gone."

Increasing frailty and a desire to spend more time with family has also sapped his appetite for political engagement. In the past year he has ducked meetings with visiting dignitaries, including the new Bolivian president, Evo Morales, and declined to comment directly or indirectly on turmoil inside his beloved African National Congress.

He announced his retirement from public life in 2004, but with his spirit undimmed few expected such a complete retreat.

"It's a pity. It's about a year now since he has made a public statement of worth," said Amina Cachalia, a lifelong friend and struggle veteran. "He is a hell of a talkative guy and I'm sure he would like to give an opinion on key issues."

Tony Leon, leader of the opposition Democratic Alliance, regretted that one of the country's few uncontested moral voices had faded. "He's here but not here. He turns up for photo ops but doesn't say much. We're impoverished by that."

After a private party at the Nelson Mandela Foundation yesterday, Mr Mandela plans to mark his birthday today with family at home in Johannesburg. Later in the week he is to attend a party at his children's fund. In a special message to children yesterday Mr Mandela stressed the importance of education and urged the wealthy to help poor children.

But on political issues he remained silent. There is no consensus on why he has gone quiet and an ANC spokesman declined to comment.

On one level the reason is obvious: the liberation hero is old, tires easily and wants to enjoy domestic life, something denied during 27 years of jail. "I am confident that nobody ... will accuse me of selfishness if I ask to spend time, while I am still in good health, with my family, my friends and also with myself," he said in 2004.

Even without his daily involvement, the foundation and other charities in his name have steamed ahead, raising millions of pounds for Aids orphans, schools and clinics.

It was widely assumed, however, that a man unafraid to criticise the US-led invasion of Iraq would continue to make occasional comments on current affairs. In recent months there have been several notable events including the rape trial of Jacob Zuma, the ANC's deputy president, and the battle to succeed Mr Mbeki. From his home and foundation headquarters in Johannesburg, nothing has been said about these or other contentious issues.

"We have noticed it," said Richard Calland of the Institute for Democracy in South Africa, a leading thinktank.

A desire to let him relax is only part of the reason Mr Mandela's advisers curtail his engagements. There is concern that his concentration is not what it was and that he might be liable to make a gaffe, according to one insider. "They are afraid to let him speak of his own accord."

There is also evidence that ANC leaders prefer the elder statesman to stay quiet. After stepping down in 1999 the Nobel peace prize laureate challenged the controversial HIV/Aids policies of his successor, Mr Mbeki, who questioned the gravity of the epidemic. After a series of public and private rows Mr Mandela prevailed, helping to shunt the government into taking the crisis more seriously, but several commentators testify to his roasting by Mbeki supporters, who accused him of disloyalty.

Mr Leon said Mr Mandela had felt chastened by the party he loved and decided against further battles. "I think he decided discretion was the better part of valour."

But a detente now appears to be under way. The quieter Mr Mandela becomes, the more Mr Mbeki lavishes him with praise, a startling reversal from the time his speeches shunned the name of his predecessor.

Reports of a pact between the two men have been bolstered by an invitation to Mr Mbeki to give this year's Nelson Mandela lecture.

Some lament Mr Mandela's silence as a loss to a ruling party riven by infighting over whether the scandal-plagued Mr Zuma should succeed Mr Mbeki. Mr Mandela's relative detachment from day-to-day affairs would equip him to moderate what has become a destabilising contest, according to Mr Calland. "His not engaging is having a negative impact on the ANC's ability to resolve its own internal crises."

Other commentators disagree. The man known by his clan name, Madiba, wields so much influence that were he to weigh in on the succession, he would overshadow the debate.

"In a family feud a wise father doesn't intervene publicly on one or the other," Gevisser said.