Cape Town, Jul 23 (IANS): Anti-apartheid icon and ailing former South African president Nelson Mandela is showing "sustained improvement" but is still in a critical condition, the presidency said.

"Mandela is still in a critical condition in hospital, but shows sustained improvement," Xinhua quoted presidential spokesman Mac Maharaj as saying.

Maharaj made the statement after President Jacob Zuma visited Mandela Monday.

Zuma assured Mandela of "love and support of all South Africans", Maharaj said.

Zuma urged people to keep praying for Mandela who spend his 44th day in hospital since June 8, his longest hospital stay in years.

This was the first official update on Mandela's health since July 18 when he turned 95.

"The birthday celebrations for the former president on July 18 were the biggest ever this year, attracting scores of South Africans who engaged in community service in honour of Madiba (Mandela's clan name)," Maharaj said.

Earlier, Mandela's grandson Mandla said his grandfather was "gaining strength every day".

After visiting his grandfather over the weekend, Mandla said Mandela will have his life support machines switched off.

He said the improvement in Mandela's health was encouraging, and that his grandfather continues to prove he has a fighting spirit.

The Nobel Peace Prize laureate has been suffering from a recurring lung infection, the result of tuberculosis developed when he was imprisoned during the apartheid.