JOHANNESBURG (REUTERS) - US President Barack Obama hailed Nelson Mandela as a "giant of justice" on Tuesday but said too many leaders in the world claimed solidarity with his struggle for freedom "but do not tolerate dissent from their own people".

Obama, speaking at a memorial in Johannesburg for Mandela, made the comment in front of an audience of leaders that included Chinese Vice President Li Yuanchao, Cuban President Raul Castro and Zimbabwe's president, Robert Mugabe.