Nelson Mandela in critical condition

The condition of former President Nelson Mandela, who is still in hospital in Pretoria, has become critical, the South African presidency said on Sunday evening.

"The doctors are doing everything possible to get his condition to improve and are ensuring that Madiba is well-looked after and is comfortable. He is in good hands," said President Jacob Zuma.

The President was also reassured that no harm came to Mandela when the ambulance taking him to hospital broke down.

"There were seven doctors in the convoy who were in full control of the situation throughout the period. He had expert medical care. The fully equipped military ICU ambulance had a full complement of specialist medical staff including intensive care specialists and ICU nurses," Zuma said. "The doctors also dismissed the media reports that Madiba suffered cardiac arrest. There is no truth at all in that report."

Mandela, South Africa's first black president, was taken to hospital in Pretoria earlier this month for the third time this year, with a lung infection.

Mac Maharaj,  Zuma's spokesman, told the BBC's Newshour that the doctors' use of the word "critical" was "sufficient explanation that should raise concern amongst us".

"Therefore we want to assure the public that the doctors are working away to try and get his condition to improve," he said.