In pictures: Mandela tributes at Pretoria hospital

A man prays as he pays his respects outside the Medi-Clinic Heart Hospital, where ailing former South African President Nelson Mandela is being treated, in Pretoria on Thursday 27 June

Messages of support for former South African President Nelson Mandela have blanketed walls and fences outside the hospital in Pretoria where he lies in a critical condition.

Children raise toward the sky after releasing the white balloons outside the hospital in Pretoria (27 June 2013)

Children release 94 white balloons - one for every year of the ex-leader's life - into the air in his honour. The former political prisoner and Nobel Peace laureate was admitted to hospital on 8 June with a stubborn lung problem which dates back to his 27 years in captivity.

Mr Mandela's relatives hold flower bouquets (27 June 2013)

Relatives of Mr Mandela collect flower bouquets left by supporters outside the hospital. South African President Jacob Zuma said on Thursday that Mr Mandela was "much better" although he still remained in a critical condition.

A woman weeps as she pays her respects outside the Medi-Clinic Heart Hospital, where ailing former South African President Nelson Mandela is being treated, in Pretoria on Thursday 27 June

On Thursday, amid news that his condition had deteriorated further, sombre well-wishers gathered. Emotional crowds outside the hospital have been singing hymns and putting up poster tributes to the man known to many as "Madiba" - his clan name.

A handwritten poster against railings outside the hospital reads: "You taught us selflessness and forgiveness"

Mr Mandela is revered for leading the fight against white minority rule in South Africa and going on to preach reconciliation despite being imprisoned for 27 years.

Members of the ruling African National Congress (ANC) party supporters dance outside the hospital (27 June 2013)

Members of the ruling African National Congress party dance outside the hospital in support of the former president. Mr Mandela retired from public life in 2004 and has rarely been seen at official events since.

A young child's poster in coloured crayon reads: "Ciao Nelson Grazie"

The makeshift campsite sprang up in front of the hospital as international television and radio crews gathered to bring word of Mr Mandela's health, competing with his supporters for space on the pavement by the written tributes.

A mass-produced balloon against the railings bears the message: "Get well soon!"

Many of Nelson Mandela's supporters' messages wish him a peaceful end. Others are more optimistic.

Messages of gratitude from those who took part in a Youth Day march

Many tributes are from children and young people not even born when the former leader was still in power.

A choir of children dressed in identical blue shirts from the Thand Uxolo Day Care centre in Pretoria sings for Mr Mandela, their hands against their hearts

Mr Mandela's health threatens to overshadow the second visit to Africa by US President Barack Obama. He is in Senegal and scheduled to travel to South Africa on Friday.