ANC Youth League leader Julius Malema was still in hospital on Friday, the SABC reported.
Limpopo Medi-Clinic spokeswoman Istha McMillan told the broadcaster he was receiving treatment and was still in bed.
She did not give further detail.
Malema was admitted to the hospital on Wednesday for flu-like symptoms.
The ANCYL said he was in a stable condition, adding that a doctor requested he stay in hospital for observation until he was in full health.
"The reasons for the hospitalisation are not major. He will be discharged soon," it said in a statement on Thursday.
It declined to give more details on his condition, saying Malema's health was a private matter.
Malema's disciplinary hearing was postponed to the October 15.
He faces charges of bringing the ANC into disrepute and sowing division within party ranks.
He recently said the ANCYL would send a team to Botswana to consolidate local opposition parties and help bring about regime change.
Charged with him are ANCYL spokesman Floyd Shivambu, deputy president Ronald Lamola, treasurer general Pule Mabe, secretary general Sindiso Magaqa and deputy secretary general Kenetswe Mosenogi.
