Nelson Mandela mourns his sister and last surviving sibling January 30, 2012 -- Updated 1112 GMT (1912 HKT) Mandela's sister, 81, dies over the weekend Her death comes the same weekend Mandela returns to Johannesburg Despite his rare appearances, Mandela retains his popularity (CNN) -- South Africa sent condolences to Nelson Mandela on Monday following the death of his youngest sister and last surviving sibling out of 31 others. Nokuthamba Mandela, 81, died Saturday, South African President Jacob Zuma said. The cause of death was unclear. "On behalf of myself, the people and government of South Africa, I would like to convey our heartfelt condolences to Madiba and the entire Mandela family at this difficult time," Zuma said in a statement. Our thoughts and prayers go out to you in this time of sorrow. His sister's death came the same weekend he returned to Johannesburg while his home in Qunu undergoes repairs. Mandela, 93, has been living at the house in the Eastern Cape province since last year. Despite his rare appearances following a respiratory infection, Mandela retains his popularity and is considered the founding father and hero of South Africa's democracy.