FORMER US President Barack Obama delivered a speech to mark the centenary of the birth of Nelson Mandela today, despite widespread calls for the invitation to be withdrawn.

Mr Obama addressed crowds in Johannesburg today as they gathered to celebrate the life of the revolutionary leader who died in December 2013.

However activists had applied pressure on the Nelson Mandela Foundation to cancel the invitation, saying Mr Obama does not represent the anti-apartheid hero’s legacy.

In an open letter earlier this year the Cage Africa advocacy group said Mr Obama was responsible during his time as US president for the expansion of military operations across Africa including drone attacks and the dismantling of Libya.

"Giving this man a platform would be tantamount to condoning these actions, something that Nelson Mandela would surely have stood against.

"This is especially pertinent given Nelson Mandela's legacy as an individual who was also once designated a 'terrorist' and suffered torture and imprisonment as a result, and who despite this is now regarded as one of the pre-eminent figureheads for justice around the world,” the letter read.

Speaking to Al Jazeera yesterday, US philosopher Cornel West said Mr Obama “was never the revolutionary Nelson Mandela was,” calling him the “face of the American empire.”

“He was always a neoliberal politician,” the intellectual continued, stressing the importance of holding Mr Obama’s politics to account.

Mr West said: “He has, in my view, committed war crimes with his drones in Pakistan and Yemen and Somalia and Libya,” saying he stood in solidarity with the protesters.

“Now, the last thing you want to do is act as if Barack Obama is some kind of grand progressive figure. No, he was a neoliberal counterfeit,” he added.

Around 9,000 people attended the Johannesburg speech in which Mr Obama said more action was needed to fulfil Mr Mandela’s vision for the future.

"It turns out, as we are seeing in this recent drift into reactionary politics, the struggle for basic justice is never truly finished," he told the crowds.

In a perceived condemnation of US President Donald Trump he said there can be no excuse for immigration policies based on race, religion or ethnicity.

Mr Obama concluded with the words of Mr Mandela, saying: "No one is born hating another person because of the colour of his skin, or his background, or his religion.”

South African President Cyril Ramaphosa received a warm response from the crowds.