Family Members Visit Ailing South Africa Icon Winnie Madikizela-Mandela (right), the first wife of former Nelson Mandela, arrives at the Mediclinic Heart Hospital in Pretoria, where Mr Mandela has been hospitalised as a result of a lung infection. Johannesburg: Nelson Mandela is showing no sign of improvement as he battles a lung infection in a Pretoria clinic where he was admitted four days ago, the South African government says. President Jacob Zuma said in a statement the anti-apartheid icon remains in "serious but stable" condition while being treated in intensive care. Amid growing fears about the 94-year-old's condition, family members were seen entering the Mediclinic Heart Hospital in Pretoria to be at his bedside. Security was tightened around the private specialist facility, where a dozen armed police stood guard outside and incoming vehicles and pedestrians were searched amid a heavy media presence. "They are there to protect the members of his family who come to visit him," said a police sergeant, asking not to be named. Mr Mandela's daughters Makaziwe and Zindzi, as well as former wife Winnie Madikizela-Mandela, were seen entering the hospital on Tuesday. His current wife Grace Machel called off a trip to London last week to be with her ailing husband. Mr Zuma's office said he had a "thorough briefing" from Mr Mandela's doctors late on Monday. "President Zuma has full confidence in the medical team, and is satisfied that they are doing their best to make Madiba better," said the statement, using Mr Mandela's clan name. Medical experts say the recurrent infection could be life threatening. Tuesday marked 49 years to the day since Mandela was sentenced to life in prison in 1964 for conspiring to overthrow the apartheid government. He spent much of the subsequent 27 years behind bars on wind-swept Robben Island, near Cape Town, where he contracted tuberculosis. Mr Mandela's latest health scare has been met with a growing acceptance among South Africans that their hero, who became the first black leader of the country after historic all-race elections in 1994, may be nearing the end of his life.