Nelson Mandela, who is still in hospital, has taken a turn for the worse and is now in critical condition, South African President Jacob Zuma said Sunday.

A statement posted on the presidential website Sunday said Zuma and Deputy President Cyril Ramaphosa visited Mandela Sunday evening in hospital.

They were briefed by the medical team who informed them that Mandela’s condition had become critical over the past 24 hours.

“The doctors are doing everything possible to get his condition to improve,” said Zuma, adding that Mandela is being well-cared for and is comfortable.

They also met with Mandela’s wife Graca Machel in hospital.

Zuma has appealed to the nation and the world to pray for Mandela, his family and the medical team that is attending to him.

Mandela was taken to a hospital in Pretoria on June 8 to be treated for a recurring lung infection.

On Thursday, Mandela’s grandson Ndaba told reporters that his grandfather’s health was improving, and the family had hoped he would be released from hospital soon.

“Positively we can say that he has been getting better and better each day and hopefully he'll be coming home soon,” Ndaba Mandela was quoted as saying by The Star, a South African newspaper.

Ndaba spoke at a media briefing about a football invitational that is expected to be part of celebrations marking Mandela’s 95th birthday next month.

Mandela was jailed for 27 years under apartheid rule. He was released in 1990 and four years later became South Africa’s first black president following the end of apartheid.