Nelson Mandela's grandson has thanked the world for its support - as the health of the former South African President worsens.

Mandela, 94, is now in a critical condition in hospital where he's being treated for a lung infection.

His oldest grandson Chief Mandla Mandela has been speaking in Cape Town:

South African President Jacob Zuma has confirmed that Nelson Mandela remains in a critical condition after his health deteriorated over the weekend.

He and ANC Deputy President Cyril Ramaphosa visited Mr Mandela in hospital on Sunday evening.

This morning Mr Zuma said there are no further details on the former President's condition, but  thanked journalists around the world:

Prolonged illness

Mr Mandela has suffered repeated bouts of illness in recent months and has been admitted to hospital four times since December.

The anti-apartheid leader has been in intensive care since he was last admitted to hospital on June 8 for a recurring lung infection.

Mr Zuma appealed to South Africans and to the world to pray for Mr Mandela, his family and the medical team attending to him.

Ambulance breakdown

In Sunday's statement, Mr Zuma also discussed the government's acknowledgement a day earlier that an ambulance carrying Mr Mandela to the hospital two weeks ago had broken down.

"There were 7 doctors in the convoy who were in full control of the situation throughout the period. He had expert medical care," Mr Zuma said.

"The fully equipped military ICU ambulance had a full complement of specialist medical staff including intensive care specialists and ICU nurses.

"The doctors also dismissed the media reports that Madiba suffered cardiac arrest. There is no truth at all in that report."

Angelique Serrou is a reporter with The Star Newspaper in South Africa - she spoke to Newstalk's Breakfast presenter this morning:

Mr Mandela is seen by many around the world as a symbol of reconciliation.

He played a leading role in steering South Africa from the apartheid era to democracy, becoming the country's first black President in all-race elections in 1994.