The African National Congress (ANC) has until December to honour the late Ahmed Kathrada's call for President Jacob Zuma to resign, former ANC treasurer Mathews Phosa said on Wednesday.

"The ANC need to come to their senses and resolve their problems before it is too late or they will bury themselves alive," he told News24 in a telephonic interview.

He was speaking shortly before leaving to attend the ANC veteran's funeral at Westpark Cemetery.

"The December 17 conference will be a trying moment for them if they do not make up their mind and honour our fallen cadre's wishes to remove Jacob Zuma," he said, referring to the party's elective conference.

He always seconded Kathrada's call for Zuma to resign.

"Uncle Kathy took a stand against Zuma and was not afraid to speak the truth; I have always supported him on his call for Zuma to step down and I know that now is a better time than ever."

Phosa said South Africa had lost an unblemished soul and a man with dignity and moral standing. He represented everything that was good about ANC.

Phosa said every ANC cadre should commit to memory Kathrada's 2016 letter to Zuma to resign.

"A president is one that must at all times unite this country behind a vision and programme that seeks to make tomorrow a better day than today for all South Africans. It is a position that requires the respect of all South Africans, which of course must be earned at all times," Kathrada wrote.