Mandela 'Improved' As Obama Arrives In SA

US President Barack Obama has insisted he will not press for a meeting with Nelson Mandela as he arrives in South Africa on an official visit.

The US leader arrived in Johannesburg with his family but had told reporters in Dakar, Senegal, before he departed for South Africa that he "did not need a photo op" with the anti-apartheid icon.

It comes after Mandela's ex-wife Winnie Madikizela-Mandela said the former South African president's condition has shown "great improvement" over recent days.

Speaking outside the Pretoria hospital where the 94-year-old is being treated for a recurring lung infection, she said he remained "unwell".

She said: "It becomes very difficult to understand the seeming impatience and statements like: 'It is time for the family to let go'.

"And statements like: 'We are praying for the family not to pull the tubes'.

"Those are insensitive statements that none of you would want made about your parents and grandparents."

Her remarks come one day after Mr Mandela's daughter, Makaziwe Mandela, criticised "vultures" in the media, saying interest in the first black South African's illness had "gone overboard".

Supporters have been praying, singing and dancing outside the Mediclinic Heart Hospital where South Africa's first black president was taken three weeks ago.

Before boarding Air Force One to Johannesburg, Mr Obama said: "I don't need a photo op and the last thing I want to do is to be in any way obstrusive at a time when the family is concerned with Nelson Mandela's condition.

"I think the main message we'll want to deliver, if not directly to him, but to his family, is simply profound gratitude for his leadership."

Mr Obama was expected to meet with US consulate staff after arriving in Johannesburg on Friday. He will then meet with South African President Jacob Zuma on Saturday.

Mr Mandela, South Africa's first black president, was taken to hospital three weeks ago with recurrent lung problems.

He turns 95 next month.

On the eve of Mr Obama's visit, Mr Mandela was said to be in a critical condition, but had stabilised since a scare forced President Jacob Zuma to cancel a trip to neighbouring Mozambique.

Yet South Africans, including Mr Mandela's family, remain braced for the worst.

"I won't lie. It doesn't look good," daughter Makaziwe Mandela said. She added that "if we speak to him he responds and tries to open his eyes - he's still there".

"Anything is imminent, but I want to emphasise again that it is only God who knows when the time to go is," she told local radio.

Mr Obama, who is currently on a three-nation Africa tour, has led a chorus of support for the man he has dubbed a "hero for the world".

"The President will be speaking to the legacy of Nelson Mandela and that will be a significant part of our time in South Africa," said deputy national security advisor Ben Rhodes.

"The President will treasure any opportunity he has to celebrate that legacy."