In a press conference on Monday morning, President Jacob Zuma said he had been told that the ex-president remained in critical condition.

Zuma described briefly meeting Mandela Sunday evening, saying he was "asleep."

"Given the hour that we got to the hospital it was late, he was already asleep," he said. "[We] saw him and then we had a bit of a discussion with the doctors as well as his wife, Graca Machel, and we left."

Zuma would not give any details about Mandela's condition, saying he "was not a doctor," but did say in a previous statement Sunday that doctors were working as hard as they could to help the anti-apartheid leader.

"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," Zuma said, using Mandela's clan name.

Zuma called on South Africans and people across the world to pray for Mandela, his family and the medical staff looking after him. In the statement, Zuma also dismissed reports that Mandela had suffered a cardiac arrest. "There is no truth at all in that report," he said.

Zuma, accompanied to the hospital by the deputy president of the ruling African National Congress (ANC) Cyril Ramaphosa, also met Mandela's wife Graca Machel.

Ambulance delay controversy

President Zuma also addressed criticism about a 40-minute delay in Mandela's transfer to hospital during a previous health scare earlier this month when he had to be moved between vehicles after a military ambulance developed engine trouble. Mandela had suffered no harm as a result of the wait on the 55-kilometer (30 mile) journey from his home in Johannesburg to a specialist heart clinic in Pretoria, said Zuma.

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

Mandela has been hospitalized four times since December, mostly due to the lung condition that has plagued him for a number of years. Jailed for 27 years under South Africa's racist apartheid system, he played a leading role in steering the country to democracy, becoming president in 1994.

rc,dr/mkg (AP, AFP, dpa, Reuters)