World leaders pay homage to Mandela at memorial service

"It is hard to eulogise any man...How much harder to do so for a giant of history, who moved a nation toward justice, and in the process moved billions around the world," Obama said in a 20-minute speech punctuated by reference to the struggle for racial freedom in Africa and America.

Pranab Mukherjee, who headed a high level Indian delegation including Sonia Gandhi and Sushma Swaraj, in his eulogy, called Mandela an icon of irreversible social and economic change who never diminished his commitment to his kind of 'satyagraha' against injustice and inequality.

Obama also referred to Mahatma Gandhi when he said that Mandela, like Gandhi, led a resistance movement that at its start held little prospect of success.

UN Secretary General Ban ki Moon, African leaders including Robert Mugabe, the last white President F W de Klerk, Chinese Vice President Li Yuanchao and Afghanistan President Hamid Karzai were among the other leaders present.

The other world leaders on the stage included present and former Prime Ministers of Britain, French President Hollande and former Presidents including Jimmy Carter, George Bush, Bill Clinton and Nicolas Sarkozy.