Nelson Mandela’s relatives have flown from around the world to be at his bedside, as the former South African president faces a fourth day in hospital.

Mr Mandela’s wife Graca Machel cancelled an appearance in London to visit the 94-year-old in the Pretoria hospital where he is being treated for a recurrent lung infection, while his eldest daughter Zenani Mandela-Dlamini returned from Argentina, where she is the South African ambassador.

Winnie Madikizela-Mandela also travelled to visit her ex-husband, who has been in intensive care since being taken to hospital on Saturday – his third admittance for a lung infection this year.

Mr Mandela’s granddaughters have also been seen coming and going from the hospital over the last couple of days, while another daughter Zindzi Mandela was yesterday reported as saying: “I've seen my father and he is well. He is a fighter”.

The office of South African President Jacob Zuma said Mr Mandela remains in a serious but stable condition, adding: “President Jacob Zuma reiterates his call for South Africa to pray for Madiba and the family during this time.”

The foundation led by retired Archbishop Desmond Tutu released a statement describing Mr Mandela as “an extraordinary gift”.

The foundation added: “As the beloved father of our nation, Nelson Mandela once again endures the ravages of time in hospital… Our prayers are for his comfort and his dignity”.

In December last year, Mr Mandela spent 18 days undergoing treatment for a lung infection and gallstones.

Before becoming South African president in 1994, Mr Mandela spent 27 years in Robben Island prison, where he contracted tuberculosis.

It is believed that the disease permanently damaged his lungs, indirectly leading to the numerous infections he has suffered since retiring from public life in 2004.