Security tightens at hospital where Mandela being treated UPI 6/11/2013 10:49:10 AM PRETORIA, South Africa, June 11 (UPI) -- Security was increased at a Pretoria hospital where former South African leader Nelson Mandela is being treated for a recurring lung condition, officials said. Police placed barriers around entrances to the facility Tuesday, as well as began checking vehicles trying to enter the hospital's grounds, CNN reported. Mandela, the country's first black president and Nobel Peace Prize laureate, was taken to the hospital Saturday. The South African president's office that day said the 94-year-old former leader was in "serious but stable condition." The government said Monday Mandela's condition was "unchanged." Mandela has been in and out of hospitals several times in recent years. He hasn't appeared in public since South Africa hosted the World Cup in 2010. His daughter Zenani Dlamini, South Africa's ambassador to Argentina, flew to South Africa to be with her father, CNN said. Mandela's former wife, Winnie, an African National Congress lawmaker, visited him Monday. Last year, he was hospitalized in December for treatment of a lung infection and gallstones.