JOHANNESBURG (AFP) - Nelson Mandela's health is improving and he will continue to receive treatment for a recurrence of pneumonia, the South African presidency said Sunday, as the anti-apartheid icon spent a fifth night in hospital.

Doctors "have reported a further improvement in his condition," President Jacob Zuma's office said he "had a restful day and continues to receive treatment." The frail 94-year-old, one of the towering figures of modern history, was admitted late Wednesday for his third hospitalisation in four months.

Doctors drained a build-up of fluid, known as a pleural effusion or "water on the lungs", that had developed from the lung infection.

That procedure helped him "breathe without difficulty," Mr Zuma's office said on Saturday. It was unclear how long South Africa's first black president would remain hospitalised. Last year he had an 18-day hospital stint in December.

Mr Mandela's recent health troubles saw an outpouring of prayers as Christians celebrated Easter Sunday, but have also seen South Africans come to terms with the mortality of the revered Nobel Peace Prize winner.

"Yes, we are concerned that he is ailing, and he is getting worse, naturally we should be concerned. I think this is the question in the back of many of our minds, when is the end? Is he going to die?"

Father Sebastian Rossouw, an assistant parish priest at the Regina Mundi Catholic Church in Soweto township told worshippers.

"We should rather celebrate what he stood for, and what he continues to stand for, that he has been an icon of peace, an icon of service," he said at the church, once a pivotal centre in the resistance against apartheid.

At home and abroad, the former president is idolised and revered as the architect of South Africa's peaceful transition from white minority-ruled police state to hope-filled democracy.

Nearly 20 years after he came to power in 1994, Mr Mandela remains a unifying symbol in a country still riven by racial tensions and deep inequality.

Renowned lawyer and Mandela's friend Gorge Bizos was confident Mandela would pull through the latest bout of illness.

"I know he has come out of quite serious illnesses before," Mr Bizos told Eye Witness News.

It is the second time this month that Mandela has been hospitalised, after spending a night for check-ups on March 9.

That followed a nearly three-week hospital stay in December for another lung infection and gallstone surgery, his longest since he walked free from jail in 1990.

He was diagnosed with early-stage tuberculosis in 1988 during his 27-year jail term and has long had problems with his lungs. He has also had treatment for prostate cancer and has suffered stomach ailments.

Pleural effusion is the accumulation of water between the lining covering the lung and that of the chest wall, experts say Having the fluid tapped was normally a minor procedure, but other cases required the fluid to be chemically broken down if it had formed pockets," according to Keertan Dheda, professor of respiratory medicine at the University of Cape Town. A minor operation would be carried out if infected.

But with age "the longer pneumonia takes to get better," and "a bit more complicated the older you get," said Dheda.

French pulmonologist Jean-Christophe Renaud said Mandela had a good constitution and could recover well.

While Mandela's legacy continues to loom large, he has long since exited the political stage and for the country's youthful population he is a figure from another era who served as president for just one term.

He has not appeared in public since July 2010.

Labour unrest, high-profile crimes, grinding poverty and corruption scandals have effectively ended the honeymoon enjoyed after Mandela ushered in the "Rainbow Nation". But his decades-long struggle against apartheid still resonates.

Meantime Mr Zuma has expressed appreciation for the prayers said for Mandela on during the Easter weekend.

Mandela's grand daughter Ndileka who attended one of the prayer sessions in Midvaal, a municipality on the outskirts of Johannesburg said the prayers are strengthening.

"I feel fortified and strong," she said.

The African Union chief, South Africa's former minister Nkosazana Dlamini-Zuma also wished Mr Mandela "all the best."