Former President Nelson Mandela underwent minor surgery to determine the cause of a stomach complaint and the 93-year-old "is as fine as can be at his age,” South Africa’s defense minister said Sunday.Lindiwe Sisulu told reporters in Cape Town that Mandela had undergone a laparoscopy on Saturday, according to the South African Press Association."It is not the kind of surgery you are thinking about. It’s noninvasive, but nonetheless investigative,” Sisulu was quoted as saying.Surgeons make an incision in the belly to insert a thin, lighted tube to look at abdominal organs during laparoscopy.The military took charge of Mandela’s health care after he spent several days in a private hospital last year with a respiratory infection. Officials have not disclosed where he is being treated this time to protect his privacy.South African President Jacob Zuma released a statement Sunday saying Mandela had a good night’s rest in the hospital. Zuma previously said Mandela was expected to go home Sunday or Monday."He is surrounded by his family and is relaxed and comfortable. The doctors are happy with the progress he is making,” Zuma said."The doctors have assured us that there is nothing to worry about and that Madiba is in good health,” added Zuma, referring to Mandela by his clan name.Mandela, a Nobel peace laureate who spent 27 years in prison for fighting racist white rule, became South Africa’s first black president in 1994 and served one five-year term. He has officially retired and last appeared in public in July 2010.