JOHANNESBURG  — South Africans on Saturday said their thoughts were with former President Nelson Mandela, who was in “serious but stable” condition after being taken to a hospital to be treated for a recurring lung infection.

Mandela, who is 94 years old, was treated in a hospital several times in recent months, with the last discharge coming on April 6 after doctors diagnosed him with pneumonia and drained fluid from his lung area. He has been particularly vulnerable to respiratory problems since contracting tuberculosis during his 27-year imprisonment under apartheid.