Former South African president Nelson Mandela's condition deteriorated to "critical" on Sunday, the government said, two weeks after the 94-year-old anti-apartheid leader was admitted to hospital with a lung infection.
President Jacob Zuma and the deputy leader of the ruling African National Congress (ANC), Cyril Ramaphosa, visited Mandela in his Pretoria hospital, where doctors said his condition had worsened in the last 24 hours, a statement said.
"The doctors are doing everything possible to get his condition to improve and are ensuring that Madiba is well looked after and is comfortable," it said, referring to Mandela by his clan name.
Mandela, who became South Africa's first black president, in 1994, was rushed to a Pretoria hospital on June 8 with a recurrence of a lung infection, his fourth hospitalisation in six months.
Until Sunday, official communiques had described his condition has "serious but stable" although comments last week from Mandela family members and his presidential successor, Thabo Mbeki, suggested he was on the mend.
The description of his condition as critical is bound to concern South Africa's 53 million people, most of whom revere Mandela as the architect of the peaceful transition to democracy after three centuries of white domination.
However since stepping down in 1999 after one term in office he has played little role in public life. His last public appearance was at the final of the soccer World Cup in Johannesburg's Soccer City stadium in July 2010.
Mandela's history of lung problems dates back to his time at Robben Island prison near Cape Town. He was released in 1990 after 27 years and went on to serve as president from 1994 to 1999.