Obama honours Desmond Tutu

President Barack Obama says South African Archbishop Desmond Tutu is a "moral titan" who will be missed as he formally retires from public life Thursday on his 79th birthday.

Obama says the Nobel Peace Prize laureate has been a voice of principle, an unrelenting champion of justice and a dedicated peacemaker.

Tutu played a pivotal role in South Africa's struggle against apartheid, the now-abolished system of white-minority rule. He also has advocated freedom and justice worldwide, supported gay rights and pushed for treatment programs to stop the spread of HIV/AIDS.

Tutu announced this year that he would retire on his birthday, Oct. 7, to spend more time with his family.