JOHANNESBURG (AP) - South Africa's president on Monday said a critically ill Nelson Mandela was "asleep" when he visited the 94-year-old at the hospital, and he urged the country to pray for Mr Mandela, describing him as the "father of democracy" who made extraordinary sacrifices on behalf of his people.

President Jacob Zuma told dozens of foreign and South African journalists that doctors are doing everything possible to help the former president feel comfortable on his 17th day in a Pretoria hospital, but refused to give details of Mr Mandela's condition, saying: "I'm not a doctor."

The briefing came a day after the government said Mandela's condition had deteriorated and was now critical.

Monday's press gathering highlighted the tension between the government's reluctance to share more information about Mr Mandela on the basis of doctor-patient confidentiality, and media appeals for thorough updates on a figure of global interest. The government's belated acknowledgement that an ambulance carrying Mr Mandela to the hospital on June 8 broke down has fuelled the debate about transparency versus the right to privacy.

President Zuma's briefing was also an indicator of the extent to which reports on Mr Mandela's health sometimes overshadow the business of the state. Under questioning, President Zuma said President Barack Obama would go ahead with a visit to South Africa, despite concerns about Mr Mandela's health.

"President Obama is visiting South Africa," President Zuma said. "I don't think you stop a visit because somebody's sick." President Obama, who arrives in Africa this week, will visit Senegal, South Africa and Tanzania.

President Zuma, who in the past has given an overly sunny view of Mr Mandela's health, briefly spoke of his visit on Sunday night to Mr Mandela in the hospital in the capital. That visit was mentioned in a presidential statement on the same night that said Mr Mandela, previously described as being in serious but stable condition, had lapsed into critical condition within the previous 24 hours.

"It was late, he was already asleep," President Zuma said. "And we then had a bit of a discussion with the doctors as well as his wife, Graca Machel, and we left."

The president said South Africans should accept that Mr Mandela is old, and he urged people to pray for their former leader.

"Madiba is critical in the hospital, and this is the father of democracy. This is the man who fought and sacrificed his life to stay in prison, the longest-serving prisoner in South Africa," President Zuma said, using Mandela's clan name.

Mr Mandela, who became South Africa's first black president after the end of apartheid in 1994, was hospitalised for what the government said was a recurring lung infection. This is his fourth hospitalisation since December.

Mr Mandela was jailed for 27 years under white racist rule and was released 23 years ago, in 1990. He then played a leading role in steering the divided country from the apartheid era to an all-race democracy. As a result of his sacrifice and peacemaking efforts, he is seen by many around the world as a symbol of reconciliation.

"Nelson Mandela, for me, is like my father," South African Alex Siake said in Pretoria. "Every day, I just pray that he can recover quickly and be among us again."

The Democratic Alliance, South Africa's main opposition party, said in a statement that the news that Mr Mandela was in critical condition came "as a blow to all South Africans." President Zuma referred to the transfer of Mr Mandela from an ambulance with engine trouble to another ambulance on the night he was taken to the hospital in Pretoria.

"Nobody can predict whether the car is going to break down or not," he said. But he said he was pleased because seven doctors, including specialists, in the convoy "made all the contingencies before leaving" and Mr Mandela's health was therefore not affected.

Asked why none of Mr Mandela's doctors had been made available for a news briefing, presidential spokesman Mac Maharaj said an arrangement had been made in consultation with Mr Mandela's family whereby information would be provided through a "single source in an authoritative way".

"We've come to that arrangement on the basis that we need to respect the privacy of the family, we need to adhere to doctor-patient confidentiality," he said.

"You can be assured that what we are saying is based on agreement with the doctors," spokesman Maharaj said. Doctors approve the text of announcements on Mr Mandela's health, and believe some media reporting has transgressed professional ethics, he said.

Family members continued with visits to Mr Mandela on Monday. They included his former wife, Mrs Winnie Madikizela-Mandela.

Monday also marked the 18th anniversary of Mr Mandela's appearance at the 1995 Rugby World Cup final in Johannesburg, a day still enshrined as a hugely significant moment for South Africa.

In a move crucial in unifying sections of a previously fractured society, Mr Mandela wore a green and gold Springboks rugby jersey at the June 24 final in Johannesburg and brought all South Africans together in support of their national team - once an all-white bastion of the apartheid regime and hated by blacks.

Mr Mandela shook hands with and patted the shoulder of the Springboks' captain, Mr Francois Pienaar, after South Africa won a tense final against New Zealand, underlining the new president's dedication to reconciliation.