JOHANNESBURG — Nelson Mandela, the former South African president and anti-apartheid leader, was admitted to a hospital on Saturday for a scheduled medical checkup, and doctors say there is no cause for “alarm,” the president’s office said.

Officials have used similarly soothing language to explain previous hospital stays for 94-year-old Mandela, but in those cases he later turned out to have more serious conditions.

The intense privacy surrounding the health of Mandela reflects in part the official reverence for a man who is seen as one of the great, unifying figures of the 20th century for helping to avert race-driven chaos in South Africa’s tense transition from apartheid to democracy.

Presidential spokesman Mac Maharaj said Mandela went on Saturday afternoon for tests “to manage existing conditions in line with his age” at a hospital in Pretoria, the capital.

“Doctors are conducting tests and have thus far indicated that there is no reason for any alarm,” Maharaj said in a statement.

He appealed for the public to respect the privacy of Mandela and his family.

Mandela was hospitalized for nearly three weeks in December before going home on Dec. 26.

At that time, he was treated for a lung infection and had a surgical procedure to remove gallstones. The ex-president has become increasingly frail.