Pretoria , South Africa ( CNN ) -- Authorities increased security around a Pretoria hospital where former South African leader Nelson Mandela remained in intensive care , three days after being rushed there with a recurring lung infection . Police set up gates and fences around entrances to the facility Tuesday , closely checking vehicles trying to gain access . The increasingly frail Mandela was taken to a hospital in Pretoria on Saturday . Later in the day , the South African president 's office said the 94-year-old former leader was in a `` serious but stable condition . '' He was breathing on his own and his wife was by his side , the office said at the time . The government said Tuesday that Mandela 's condition remained unchanged . President Jacob Zuma visited Mandela late Monday and was satisfied with the medical care he was receiving . `` Yesterday I met the team of doctors who are treating him , '' Zuma told a reporter . `` They gave me a very thorough briefing and really I was very confident that they know what they are doing and they are doing a good job . Whilst it is very serious , he is stabilized . And we are all praying for him to recuperate quickly . '' Meanwhile , Mandela 's daughter Zenani Dlamini , who is the South African ambassador to Argentina , has flown back to South Africa to be with her father . African National Congress lawmaker and Mandela 's ex-wife , Winnie , also visited him Monday . Mandela has been in and out of hospitals in recent years . Each episode has sparked renewed concerns . South Africa : Following Nelson Mandela . His history of lung problems dates to when he was a political prisoner on Robben Island during the apartheid era , and he has battled respiratory infections over the years . He has not appeared in public since South Africa hosted the World Cup in 2010 . Last year , he spent the Christmas holidays undergoing treatment for a lung infection and gallstones , one of his longest hospital stays since his release from prison in 1990 .
NEW : President Jacob Zuma says it 's doctors ` ` are doing a good job '' Mandela has not appeared in public since South Africa hosted the World Cup in 2010 . He has been in and out of hospital in recent years . His daughter has flown back to be with him .