Nosekeni Mandela died a year after her son was sentenced to life imprisonment.

This story was revealed yesterday by his grandson, Zwelivelile Mandla Mandela, who addressed a ceremony in Zwelitsha to celebrate the former president's release from prison 23 years ago.

"After his release, and even today, he always says there is nothing more hurting in his life, or to any human being for that matter, than the failure to be able to bury one's own mother," he said about Madiba, who turns 95 in July.

Mandla revealed that the family had mixed feelings over Mandela's release from Victor Verster prison in 1990, as some had feared for his health.

"None of us ever dreamt that he would still be alive 23 years after his release. We thank all of you for putting him in your prayers, and we urge you to continue doing so."

Mandla, an ANC MP, also used the occasion to call for unity in the ruling party.

He also urged his comrades to be open to criticism.

"The open criticism that characterised [ANC] leadership during my grandfather's time is now lacking in our lives. We tend to personalise our differences these days and that is wrong and to the detriment of our beloved movement and country."