ANC president Jacob Zuma on Friday urged those planning to leave the party to do so and "leave us in peace".

Addressing the party faithful and mourners at the funeral of anti-apartheid activist Billy Nair in Durban, he urged party members not to be "swayed into negative action by the anger arising out of the new phenomenon of ANC members who are calling a so-called convention to discuss the formation of a new political party".

"We wish the adventurists (sic) luck and are pleased that many are coming out and are resigning from the ANC.

"We expect the convention to unmask many others who will hopefully also leave us in peace without any further delay," he said.

"We remain unfazed by the occurrences of the past few weeks. The ANC is not for the faint-hearted. If it were, it would not have leaders of the calibre of Billy Nair or Nelson Mandela."

President Kgalema Motlanthe said: "Developments within the ANC over the last few weeks have for many raised the spectre of a movement rent asunder by the actions of the very people charged by history to ensure that it remains united."

Nair would want party to remain united

Motlanthe believed Nair would want the party to remain united.

"He (Nair) belonged to a generation of leaders of our movement who understood that leadership is not always about occupying a position of power," he said.

He paid tribute to Nair and Nair's family, as did Zuma. Nair's wife Elsie sat at Zuma's side during most of the proceedings, held in the packed hall of the Durban Exhibition Centre.

Chairs for 2500 people were initially placed in the hall, but more were brought in.

The event started off with many ANC members, wearing Jacob Zuma t-shirts, singing and chanting near the hall's entrance.

ANC facing many challenges

South African Communist Party secretary general Blade Nzimande said the party was facing many challenges and "was disappointed" at those who were leaving the party.

"In line with the Chinese [proverb], we will say that one should never lift a rock if it's going to fall very hard on your feet."

Cosatu president S'dumo Dlamini said he wanted to assure the ruling ANC of the organisation's support in the upcoming election.

"Our alliance is under attack by rogue elements. We have to mount our offence because we owe it to him (Nair) to consolidate an ANC victory in this province."

Other speakers included SA Revenue Service commissioner Pravin Gordhan and KwaZulu-Natal ANC chairperson Zweli Mkhize.

In a tribute handed out at the service, former president Nelson Mandela writes: "He was an outstanding South African, one whose resilience in adversity was a resource to others. His unwavering commitment made a difference in many organisations and helped to improve many people's lives."

Mandela described Nair as a fighter to the end, a comrade, a friend and a great patriot.

Former Ekurhuleni metro police chief Robert McBride and brother of convicted fraudster Schabir Shaik, Mo, were also present.

Nair died from a stroke last week. He was due to be cremated at Durban's Claire Estate Crematorium later in the day.