The statement added that he was receiving the 'best possible expert medical treatment and comfort'.
It said that the anti-apartheid hero was being treated for a 'recurrence of his lung infection' and that doctors were ensuring he had the best possible treatment.
According to the Telegraph, Zuma wished Mandela a speedy recovery and he urged South Africans and the world to pray for the former leader and his family.
Local media claim he is unable to breathe properly and has been put on a ventilator.
Mandela was admitted to hospital for nearly three weeks in December with a lung infection, and while he was there he underwent an operation to remove gall stones, the report added.