( 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 . '' The former president -- affectionately known by his clan name Madiba -- last appeared in public in the closing ceremonies of the 2010 World Cup in South Africa . 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 . Under South Africa 's apartheid regime , Mandela spent 27 years in prison after being convicted of sabotage and attempts to overthrow the government . He was released in 1990 and became president in 1994 .
Mandela 's sister , 81 , dies over the weekend . Score: 6 Despite his rare appearances , Mandela retains his popularity .