A government source told The (Gauteng) Star the condition of Mandela, 94, hospitalized for a recurrent lung condition, was "scary."
President Jacob Zuma said during the weekend the Nobel Peace Prize laureate was in "serious but stable condition" but the South African government provided no medical update Monday.
North West Prime Minister Thandi Modise asked the world to pray for Mandela.
"To many across the globe, in our country and province, Tata Madiba [as Mandela is known] is a unifier and a symbol of reconciliation. Though we know that he is not immortal like all of us, we are inspired by his fighting spirit and wish his family all the strength for them to unite in love and continue to give him all the support he needs."
Mandela's family barred all visitors -- including government leaders and senior party officials -- from visiting South Africa's first black president who was taken to Pretoria's Mediclinic Heart Hospital Saturday, government sources told the The Star Sunday.
"The old man is not well. It's scary. He's still holding on to his life, but it's bad," one source told The Star. "The family don't want visitors because of his condition. They told the hospital not to allow anyone in because they are a distraction."