President Thabo Mbeki pushed Winnie Madikizela-Mandela aside and brushed off her kiss while thousands of young people commemorating a student uprising 25 years ago on Saturday looked on.
Madikizela-Mandela's motorcade swooped into Orlando stadium in Soweto where the rally was under way, interrupting a speech by a youth leader.
The crowd cheered the popular ex-wife of former president Nelson Mandela as she strode onto the dignitaries' platform and headed for Mbeki. But as she stooped to kiss him he turned his face away and flicked his hand at her, knocking off her hat. He spoke to her angrily before she walked away to take a seat.
Asked afterwards about the incident, she replied: "Ask him ."
Meanwhile, Youth Day was commemorated throughout the country with most politicians urging young South Africans to emulate their peers of 1976.
The day marked the 25th anniversary of the bloody revolt when hundreds of Soweto pupils, protesting against the use of Afrikaans in schools, were killed and wounded by apartheid police.
At the main event on Saturay, thousands of marchers lead by Mbeki retraced the footsteps of the 1976 uprising.
Clad in a blazer and running shoes, Mbeki lead a kilometre-long procession from the Morris Isaacson school, where pupils first gathered 25 years ago.
Scores of residents lined the streets in the hopes of catching a glimpse of the president while cars with blaring speakers sent the crowd into a frenzy as they cheered.
The marchers proceeded to the Hector Petersen memorial, where Mbeki laid a wreath in memory of the victims. Petersen was the first pupil to be gunned down by apartheid police in the riots.
Addressing a packed stadium, Mbeki urged the youth to tackle their problems with the same zest displayed by their peers of 1976. He cited poverty, unemployment, racism, and the spread of HIV/Aids as the major challenges facing the youth of today.
Tony Leon, the Democratic Alliance leader, used Saturday's Youth Day commemoration to warn that young South Africans were becoming part of "a second lost generation".
In a speech prepared for delivery at a rally in Mamelodi outside Pretoria, Leon said Aids, skills lost to the country, unemployment and murder were some of the problems facing the country's youth.
"I look to the young people of today, not as tribunes of the past struggle, but as inheritors of a very uncertain future," Leon said.
Lionel Mtshali, the KwaZulu-Natal premier, told a Youth Day rally in Ulundi that young people should be more wary of HIV/Aids given the prevalence of the disease in the province, which has the highest infection rate in the country.
At Hibberdene on the province's south coast, Zulu King Goodwill Zwelithini and United Nations Children's Fund goodwill ambassador Harry Belafonte opened the loveLife youth centre at Emaphulini. - Reuters-Sap