Former surgeon general of the South African National Defence Force Dr Vejaynand Ramlakan.
Dr Vejaynand Ramlakan, the former surgeon general of the South African National Defence Force, was driven to the Mediclinic Heart Hospital in Pretoria on Wednesday.
His car was not searched by police and security guards, despite security at the private hospital being stepped up since Mandela was admitted on June 8 with a recurring lung infection.
The doctor has been heavily involved in Mandela's care over the past few years, and was at his side when he was discharged from hospital in 2011 following a respiratory infection.
Ramlakan was imprisoned on Robben Island between 1987 and 1991, and joined the armed wing of the ANC in 1977.
Police started searching vehicles entering the facility at about 5am.
Earlier, Tshwane Metro police officers barricaded part of Celliers Street leading to the hospital's main entrance and numerous traffic patrol cars were also in the area.
Well wishes
Local residents asked about the health of the former statesman while walking past the hospital.
Burning candles, bouquets of pink and red flowers, paintings, and hundreds of messages adorned the wall at the main entrance.
Well-wishers transformed the wall outside the hospital into a miniature art gallery with presents, get-well cards, balloons and floral tributes in support of Mandela.
The presidency said on Tuesday that the anti-apartheid icon remained in a critical condition.
"[Mandela's] condition remains unchanged in hospital, and doctors continue to do their best to ensure his recovery, well-being and comfort," spokesperson Mac Maharaj said in a statement. – Sapa