An ambulance carrying Nelson Mandela to a hospital two weeks ago developed engine trouble, delaying the 94-year-from reaching hospital for 40 minutes, it has emerged.
The South African government confirmed the ambulance had developed engine trouble and that Mr Mandela had to be transferred to another ambulance for the remainder of his journey to the hospital.
Care was taken to ensure the condition of the former president was not affected, it said in a statement from the office of President Jacob Zuma.
The government said doctors are satisfied that the Nobel Peace Prize laureate suffered "no harm" at the time. The anti-apartheid leader remains in serious but stable condition in hospital.
The government confirmed reports about transport problems when the former leader was taken to the hospital for what officials have said is a recurring lung infection.
CBS News reported that Mr Mandela had to be transferred in wintertime temperatures to another ambulance in the early morning of June 8 after waiting on the side of the road for 40 minutes.
Mr Mandela was taken from his home in the Johannesburg neighbourhood of Houghton to a hospital in Pretoria, the capital, about 31 miles away.
"The fully equipped military ICU ambulance had a full complement of specialist medical staff including intensive care specialists and ICU nurses. The convoy also included two quick response vehicles," the presidency said.
"When the ambulance experienced engine problems it was decided that it would be best to transfer to another military ambulance which itself was accompanied for the rest of the journey by a civilian ambulance."
The statement added: "All care was taken to ensure that the former president Mandela's medical condition was not compromised by the unforeseen incident."