A few dozen members of the ANC Youth League's Pretoria branch sang struggle songs outside the Pretoria hospital where former president Nelson Mandela remained in a critical condition on Thursday.

The group arrived around midday, shortly after the ailing icon's relatives left the hospital.

The Celliers Street entrance to the facility remained cordoned off, and police and security guards searched cars entering the premises.

The Youth League members released white balloons for former President Nelson Mandela to show their support.

Deputy Secretary of ANCYL Nkhensani Kubayi says: "We have to show our support and unite as Africans for Madiba"

Earlier on Thursday, family members broke their usual visit routine and collected flowers that well-wishers have placed outside the Medi-Clinic Heart Hospital.

Ndileka Mandela, a granddaughter of the anti-apartheid icon, said he was in a critical, but stable condition.

Another grandchild, Zoleka Mandela, said it had been a tough time for the family.

"He's stable, and we'd like to thank everyone for their support," Zoleka Mandela said.

Ndileka Mandela said the public exposure had not been easy for the family to deal with.

"They're [the family] anxious; he's critical but stable. Lots of comfort from the messages of support. It's harder going through this in the public eye."