South Africa and the world showered tributes on Nelson Mandela on Thursday as the anti-apartheid leader turned 95 in hospital and his doctors reported he was "steadily improving" from a six-week lung infection.

The country has been on edge since the former president and father of the multi-racial 'Rainbow Nation' established at the end of apartheid in 1994 was admitted to hospital on June 8 with recurring lung problems that kept him in a critical condition. It was his fourth stay in hospital in six months and has reminded South Africans that the man who is globally admired as a moral beacon against injustice and a symbol of racial reconciliation will not be with them forever.

But the mood was of celebration on Thursday as thousands of South Africans sang "Happy Birthday" and took part in charitable initiatives in a global outpouring of support for the Nobel Peace Prize laureate on U.N.-designated 'Nelson Mandela Day'.

U.N. Secretary-General Ban Ki-moon hailed Mandela as "a giant of our times" and called on people around the world to pay tribute to him through community service. South Africans young and old commemorated the birthday with 67 minutes of public service to honor the 67 years Mandela served humanity by first fighting against white-minority rule and then consolidating racial harmony when he was president.