JOHANNESBURG - Former President Nelson Mandela was admitted into a hospital in Pretoria Saturday afternoon for a scheduled medical check-up to manage existing conditions in line with his age, the Presidency said.

Doctors are conducting tests and have thus far indicated that there is no reason for any alarm, Presidential spokesman Mac Maharaj said.

"We appeal for privacy for Madiba and his family," Maharaji said.

This is the second time that Mandela, 94, was admitted into hospital in three months.

On December 8, he was taken into a Pretoria hospital for a lung infection and gallstones. He underwent a successful surgery to have the gallstones removed after doctors attended to his lung infection.

He was discharged from hospital on December 26 to undergo home- based high care at his Houghton home.

This was Mandela's longest hospital stay since 2001 when he underwent seven weeks of radiotherapy after being diagnosed with prostate cancer.

Mandela served as South African president from 1994 to 1999. He had spent 27 years in prison before elected the first black president in the country after the end of apartheid.