EX-South African president Nelson Mandela remains in a critical condition in hospital.
The 94-year-old anti-apartheid hero was admitted to hospital two weeks ago.
Mr Mandela, who became South Africa's first black president in 1994, was rushed to a Pretoria hospital early on June 8 with a recurring respiratory infection.
"The condition of former president Nelson Mandela, who is still in hospital in Pretoria, has become critical," a South African government spokesman said.
The presidency also confirmed that the intensive care ambulance carrying former Mr Mandela to hospital two weeks ago broke down.
Media reports said he was stranded for 40 minutes.
Presidential spokesman Mac Maharaj said the former president was transferred to another military ambulance for the remainder of the almost 50 minute journey between Johannesburg and the Medi-Clinic Heart Hospital in Pretoria.
"All care was taken to ensure that former president Mandela's medical condition was not compromised by the unforeseen incident," Mr Maharaj said.
He would not say how long Mr Mandela's journey to hospital had been delayed.