South African President Jacob Zuma has cancelled a trip to Mozambique on Thursday after visiting former leader Nelson Mandela, 94, who remains critically ill in a Pretoria hospital.

Mr Zuma's spokesman Mac Maharaj said his condition had deteriorated "in the past 48 hours".

South Africa's first black president has been in hospital since 8 June with a recurring lung infection.

Doctors were doing everything to ensure his well-being, a statement said.

Emotional crowds continue to gather outside the hospital, adding messages of support for Mr Mandela.

Correspondents say South Africans now seem resigned to the prospect of his death.

"We are all going to feel bad when he passes [away], but at the same time we will be celebrating his life. He has done so many great things for this country," said 25-year-old John Ndlovu, quoted by Reuters news agency.

Gratitude

Mr Zuma was due to attend a regional summit in the Mozambican capital Maputo on Thursday, but decided to cancel his trip.

The statement from his office said he "reiterated his gratitude on behalf of government, to all South Africans who continue to support the Madiba family".

President Zuma's decision to cancel the visit to Mozambique where he was to attend a regional infrastructure investment conference will only reinforce the impression that Nelson Mandela's life is slipping away, the BBC's Mike Wooldridge reports from Johannesburg.

But later Mr Zuma's office warned against speculation about Mr Mandela's health, saying that announcements about his condition would come from the president himself or Mr Maharaj.

Mr Maharaj criticised some media outlets for broadcasting unverified information, as rumours spread on social media sites.

Mr Mandela, known by his clan name Madiba, is revered for leading the fight against white minority rule in South Africa and then preaching reconciliation despite being imprisoned for 27 years.

He was awarded the Nobel Peace Prize in 1993 and was elected president the following year. He left office in 1999 after a single term.

Mr Mandela retired from public life in 2004 and has rarely been seen at official events since.

He has a long history of lung problems, and was diagnosed with tuberculosis in the 1980s while he was a prisoner on Robben Island.

After his release, Mr Mandela said that the tuberculosis was probably caused by dampness in his prison cell.