Former South African president and anti-apartheid leader Nelson Mandela remained in a serious but stable condition in a Pretoria hospital yesterday after treatment for a lung infection, the government said.

A statement said President Jacob Zuma had been updated by doctors on the health of the 94-year-old.

"President Zuma has full confidence in the medical team and is satisfied that they are doing their best to make Madiba better," it said, referring to Mr Mandela by his clan name.

Police tightened security around Pretoria's Medi-Clinic Heart Hospital which is treating Mr Mandela, revered for leading the struggle to end South Africa's apartheid system. Mr Mandela became South Africa's first black president in 1994.

Around a dozen police officers were deployed outside the building to keep reporters and television crews from the entrance.

This is Mr Mandela's fourth hospital stay since December, and there is a growing realisation among South Africa's people that they will one day have to say goodbye to the father of their Rainbow Nation.

Mr Mandela has received visits from family members including his wife Graca Machel and ex-wife Winnie Madikizela-Mandela.