The Archbishop of Cape Town says he is glad people are offering heartfelt prayers for the recovery of Nelson Mandela but he also welcomes the growing acceptance that the former South African President cannot go on forever.

Mandela, 94, is in hospital with a lung infection. President Jacob Zuma said his condition was critical and encouraged prayers.

"All of us in the country should accept the fact that Madiba [Nelson Mandela's clan name] is now old. As he ages, his health will ... trouble him and I think what we need to do as a country is to pray for him," he said.  

Writing in the Sunday Independent, Archbishop Thabo Makgoba said it was time for South Africans to break the taboo of death and learn to deal with mortality.

He said it troubled him that people had "become so poor at addressing this fundamental part of what it means to be truly human".

"Madiba's latest spell in hospital has had us once again dancing around the subject, though I was glad to see that alongside our heartfelt prayers for his recovery, there is also growing acceptance that he cannot go on for ever, and calls that we must learn to let him go," he said.

"This is both good and necessary, for Madiba's sake and for ours. In fact, a more honest attitude to our own mortality helps us all in the daily business of life."

He added: "Now the time is drawing close when we must do the same for Madiba. Let us not be afraid to use the ancient words of the Night Prayer – may God grant him a peaceful night, and a good end."

Mandela led the struggle to end apartheid in South Africa and spent 27 years in prison. He became the country's first black president and, after stepping down in 1999, continued to promote a message of reconciliation among South Africans.