Nelson Mandela, the former South African President, is in hospital for treatment following the recurrence of a lung infection.
The Archbishop of York, Dr John Sentamu, has issued a special prayer for Mandela, who is 94.
In his prayer, the Archbishop of York said: "Bwana Madiba, Nkosi bless you and keep you; Nkosi make his face to shine upon you and be gracious to you. Nkosi lift up his countenance upon you and be gracious to you. Peace be with you. Christ is Risen. Alleluia!"
Mandela remains an important political symbol not only for South Africa but also for the international community.
He is regarded by many South Africans as the 'father of a nation' for leading the struggle against apartheid.
He served as president from 1994 to 1999, during which time his administration worked to address the legacy of apartheid as well as eliminating racism, inequality and poverty.
Mandela has become frailer in recent years and earlier this month spent a night in hospital. Late last year, Mandela spent three weeks in a hospital based in Pretoria, where he was treated for a lung infection and gallstones.
President Jacob Zuma has told South Africans not to panic over this latest hospital visit.
In an interview with the BBC, he said the former president was doing "very well" so far.
"Of course I have been saying to people, you should bear in mind Madiba is no longer that young and if he goes for check-ups every now and again, I don't think people must be alarmed about it. I would like to really say the country must not panic," Mr Zuma said.
Mmusi Maimane, national spokesman for the opposition Democratic Alliance said: "We know that he will be in the thoughts and prayers of many people around the world today. We wish him, his family and friends all the best in this difficult time."
