Johannesburg, Jun 23 (IANS): Anti-apartheid icon and South Africa's first black president Nelson Mandela remains in a serious but stable condition in hospital, the Presidency said.

The announcement came as the ailing 94-year-old Mandela Saturday spent his 14th day in hospital in Pretoria. He was admitted with the serious lung infection June 8, Xinhua reported.

"We thank the public for support and for respecting the privacy of the former president and his family," the Presidency said in a statement.

The Presidency confirmed a media report that the military ambulance transporting Mandela June 8 from his residence in Johannesburg to Pretoria had an engine failure but it was soon replaced by another military ambulance.

"The doctors were satisfied that Mandela suffered no harm during this period," the statement said.

"We appeal again that his privacy be respected and that he be accorded the doctor-patient confidentiality that all patients are entitled to in terms of medical ethics," the Presidency said.

This is the third time that Mandela has been admitted to hospital this year. On March 27, he was hospitalised after doctors diagnosed him with pneumonia.

He was also admitted in December 2012 for his recurring lung infection.