Anti-apartheid hero Nelson Mandela hailed Barack Obama as a "new voice of hope" for the world on Tuesday and compared his inauguration as U.S. president to South Africa's historic transition to democracy.

In a letter handed to Obama before Tuesday's ceremony, the former South African leader congratulated the new president on what he called a "truly historic" moment for the United States and the world.

"We are in some ways reminded today of the excitement and enthusiasm in our own country at the time of our transition to democracy," Mandela wrote in the letter, issued on Tuesday.

"People, not only in our country but around the world, were inspired to believe that through common human effort injustice can be overcome and that together a better life for all can be achieved."

Mandela, who led South Africans in the fight against white rule and has become a global icon for freedom, said Obama's election to office had "inspired people as few other events in recent times have done".

"You, Mister President, have brought a new voice of hope that these problems can be addressed and that we can in fact change the world and make of it a better place."

Mandela said he shared in a special "excitement and pride" felt by Africans because of the ties linking Obama -- whose father was a black Kenyan -- to the continent.

"You will always be in our affection as a young man who dared to dream and to pursue that dream," Mandela wrote.

"We wish you well."