Obama to deliver speech today marking 100th anniversary of Nelson Mandela's birth

Obama is set to deliver a speech in South Africa which will mark the 100th anniversary of Nelson Mandela's birth. Tuesday's speech comes on the eve of "Mandela Day" -- his birthday, which is marked around the world every year on July 18.

The former US president will call on young people around the world to work towards fairer societies highlighting Mandela's struggle for democracy and equal rights in South Africa.

Obama is expected use the annual Nelson Mandela Lecture to highlight how Mandela, a Nobel Peace Prize winner, kept up his campaign against apartheid - or white minority rule - in spite of what appeared to be insurmountable odds.

He will also host a town hall event on July 18 for 200 young leaders selected from across Africa to attend a five-day training programme.

The former US president met Mandela only briefly in 2005 but gave a eulogy at his funeral saying Mandela "makes me want to be a better man" and hailing him as "the last great liberator of the 20th century".

Mandela was imprisoned for 27 years as part of his fight on charges of conspiring to overthrow the state, before emerging from Robben Island prison and going on to lead his nation.

South African President Cyril Ramaphosa has said he would mark the day by donating half his salary to charity to honour "the great sacrifices he made and his tireless commitment to improving the lives of the most vulnerable."

But F.W. de Klerk, the former president who shared the Nobel Peace Prize with Mandela in 1993, told AFP: "I'm convinced that President Mandela would be deeply concerned, as I am, about the present state of affairs in South Africa."

"His vision of a reconciled South Africa has become almost non-existent within the (ruling) ANC at the moment," he said.

Mandela, South Africa's first black president known locally by his clan name "Madiba", died in 2013.