"The doctors attending to former president Nelson Mandela report that he has had a comfortable 24 hours and that he remains under treatment in hospital," said presidency spokesperson Mac Maharaj on Friday.
He said doctors had not given any information about when he might be released.
Rainy weather has not discouraged news crews camping outside the Mediclinic Heart Hospital in Pretoria, in an attempt to get updates on Mandela's health.
Mandela is believed to be recuperating in the private institution, despite confirmation on Monday by Defence Minister Nosiviwe Mapisa-Nqakula that the statesperson was at a military facility.
On Friday, journalists from local and international media parked their vehicles along Celliers street, overlooking the private hospital's main entrance.
Among the media there was the Eyewitness News (EWN) team which reported that: "The name of the hospital is known by Eyewitness News, but this is not being released to respect Madiba's dignity."
That report shifted attention from the One Military Hospital at the Thaba Tshwane Military Base where the media had been camping since last weekend.
Since Friday morning, the number of journalists kept increasing at Mediclinic as details of the reported new hospital filtered through.
At around midday on Friday, a convoy of three black vehicles with police lights and sirens entered the Mediclinic Heart Hospital. Hospital security barred journalists from following the cars into the premises.
Moments later, the vehicles came out escorting a fourth one – a black military ambulance with yellow army number plates. At that stage reporters at the scene were speculating that Madiba may have been discharged.
However, journalists stationed at the One Military Hospital across town reported that the convoy entered the state facility after leaving the private hospital.
EWN reported on Thursday that Mandela, 94, was not receiving treatment at the military facility as had been widely reported after Mapisa-Nqakula's interview.
Mapisa-Nqakula spoke to reporters outside One Military Hospital after seemingly visiting Mandela there.
'It is not part of any strategy to mislead the public'
At the time, she said: "He's doing very, very well and it is important to keep him in our prayers and also to be as calm as possible and not cause a state of panic, because I think that is not what all of us need."
The presidency said it had not been the government's intention to mislead the public or the media. Maharaj said he had only stated Mandela had been admitted to a Pretoria hospital.
"It is not part of any strategy or tactic by government to mislead the public. We have never had that intention. We know to keep to the facts and we've been rigorous," he said in an interview on Talk Radio 702.
The Beeld newspaper reported that Mandela had been admitted under a pseudonym, which was known to the newspaper.
What appeared to be an emergency medical vehicle, with military number plates, was parked in the hospital manager's parking bay.
A number of men wearing electronic ear-pieces, and who were thought to be members of the VIP protection unit, had been seen moving around the hospital grounds and inside the building.
According to Beeld, Mapisa-Nqakula and senior SA National Defence Force officers had visited the hospital.
The newspaper reported that surgeon general Lieutenant General Veejay Ramlakan was there on Tuesday and Wednesday, and that Mandela's wife Graça Machel, President Jacob Zuma and former president Thabo Mbeki had also visited the hospital.
The Mediclinic Heart Hospital is next to Pretoria's Maupa Naga police station. According to its website, the hospital takes pride in being "the first and still the only hospital of its kind – a private, specialised heart hospital in South Africa".
Mandela was flown to Pretoria from his home in Qunu, in the Eastern Cape.
The presidency said he was suffering from the recurrence of a previous lung infection and was responding to treatment.
Mandela's hospital stay is his longest continuous period in hospital since 2001, when he underwent seven weeks of radiotherapy after being diagnosed with prostate cancer.
He was 83 at the time. In January 2011, Mandela was admitted to a Johannesburg hospital for an acute respiratory infection.
He had contracted tuberculosis while in prison. – Sapa