South Africa will never know peace until it resolves its longstanding land question, Kenyan academic Professor Patrick Lumumba has said.

Land has come to the fore ahead of next year's national elections as the ruling African National Congress grapples with how to transfer large tracts of prime agricultural land owned by the white minority to millions of blacks from whose ancestors it was wrested by white settlers centuries ago.

Speaking at a lecture to commemorate the 100th anniversary of the birth of global icon Nelson Mandela at Walter Sisulu University in Mthatha on Tuesday night, Lumumba said land was the last colonial question the country needed to tackle, and that the solution was dialogue.

He said ongoing land reform consultations were a step in the right direction and called upon the white minority to stop being defensive about ownership.

"How do you deal with the land question if you have a population that holds the view that this is their land?" Professor Lumumba asked. 

"If I was a white South African owning the land I would be the first to organise my people for a dialogue on how best to distribute this land. Those who own the land must be reminded that if you keep away this land from the majority there will be an untenable situation."

He said the land ownership issue in South Africa was even more complex than in fellow African state such as Kenya and Zimbabwe. 

Mandela, who died in 2013 and would have turned 100 on Wednesday, would have prescribed solutions for Africa's  problems, said Lumumba.

"He would have reminded us that that time has come to do away with dealers and have leaders instead," Lumumba said, adding the continent lacked such leadership.

The electorate had a role to play in shaping its future leadership, he noted.

The Mandela centenary lecture was organised by OR Tambo district municipality as part of global celebrations to celebrate the anti-apartheid hero.