Well-wishers are continuing to gather outside the hospital in Pretoria where former President Nelson Mandela remains in a critical condition.

They have been singing and saying prayers both outside the hospital and at his former home in Soweto.

People are anxious about his health but also want to express pride in the man many consider the father of the nation, the BBC's Karen Allen reports.

South Africa's first black president is suffering from a lung infection.

Many images of Nelson Mandela now adorn the walls and gates of the Pretoria hospital where the former president is being treated

The 94-year-old icon of the anti-apartheid struggle has now spent 20 days in hospital.

President Jacob Zuma - who cancelled a visit to Mozambique on Thursday to visit Mr Mandela in hospital - said his condition had improved, but still remained critical.

Mr Mandela's daughter Makaziwe admitted on Wednesday night after seeing him that "he doesn't look good... but... if we speak to him, he responds and tries to open his eyes".

She was also highly critical of the behaviour of the international media, accusing some of behaving like vultures with their "overboard" coverage.

Mixed emotions

An increasing number of messages of support and thanks have been posted on the hospital railings and walls.

Many contain images that capture the life of Nelson Mandela, known by his clan name Madiba.

People sang and danced in tribute during an all-night prayer vigil outside his former home in Soweto.

Children released 94 balloons - one for every year of the ex-president's life - into the air in his honour.

There are mixed emotions among the well-wishers outside the hospital, our correspondent reports. People are sad and anxious but at the same time feel deeply proud of him and his achievements.

"There is no sadness here. There is celebration. He is a giant," 57-year-old Nomhlahla Donry, whose husband served time with Mr Mandela, told the AFP news agency.

"We are saying let him live long because we like him and he has done a lot for us in this world. He's done a lot of amazing things and we really love Tata," local resident Alfred Makhathini told Reuters.

South Africa's ruling African National Congress (ANC) has said it will hold vigils each day that the former leader remains in hospital.

US President Barack Obama, who is due to fly to South Africa later on Friday, described Mr Mandela as "a hero for the world".

"His legacy will linger on through the ages," he said, while on a visit to Senegal on Thursday.

The hospital in Pretoria where Nelson Mandela remains in a critical condition has become a place of pilgrimage for his many supporters.

The walls and railings of the hospital are covered with images of the first black South African president and icon of the anti-apartheid struggle.

Many people have been bringing messages of thanks for his achievements, and expressions of hope for his recovery.

Well-wishers have been singing and dancing as well as praying for the 94-year-old.

Sadness at his failing health is mixed with a sense of national pride for a man many consider to be the father of the nation, say correspondents outside the hospital.

The ruling African National Congress says it will hold vigils every night Mr Mandela is in hospital.