In an interview with Fairfax Media, Ndaba Mandela vowed the family had united to put the bitter feuding behind it as it contemplated a future without its patriarch.

Ndaba described his grandfather's rally in recent days, a revival that has even enabled him to watch television, as a remarkable turnaround for a man who only recently appeared unlikely to reach the birthday milestone (July 18 was proclaimed as Mandela Day by the United Nations in 2009).

''He's the same [as on the weekend],'' Ndaba said of Mr Mandela's condition. ''I last saw him on Saturday and he's still critical but stable. But what I can say is that he is a lot more responsive. And what I mean is he is a little bit more alert, he is a little bit more aware, his movement's a little bit stronger, he's able to look around the room and that kind of thing.''

Asked if his grandfather could speak, however, Ndaba replied: ''No, not really.''

He said it was possible Mr Mandela was now aware of the outpouring of concern from around the world. ''I'm not sure if he's aware of the world's love but he is definitely aware of the family love.

''I know that he recently started watching TV last week. I wasn't there when he started watching TV so I'm not sure if he saw the news and saw something that showed how people were feeling and reacting.

''So maybe he is aware now.''

Of the feuding within the clan - including his brother Mandla fighting relatives in court over the burial place of three of Mr Mandela's deceased children - Ndaba said the bitterness was in the past.

''I am 100 per cent confident, yes … the majority of our family is united, that's the most important thing. Not everybody 100 per cent will be, but the majority is and that's a good thing.''

He also sent a conciliatory but stern message to his estranged brother over the dispute.

''I can definitely forgive him for what he did. He is my brother, he will always be my brother, that will never change.

''I hope he understands what he has done, that it really disturbed us and I hope that he is apologetic in his heart.''

Ndaba said this year's Mandela Day was a turning point as the event began to grow in international stature.

The day is built around the ''67 Minutes for Mandela'' initiative - named in honour of his 67 years of public service - with people encouraged to devote 67 minutes to an activity helping others.

Ndaba advised Australians to pay their 67-minute tribute in whatever way they saw fit.

''It can be anything that benefits somebody other than yourself.''