The sacrifice of murdered anti-apartheid activists, the Pepco Three and Cosas Two, will not be forgotten, President Jacob Zuma said at the burial of their remains on Saturday in Port Elizabeth.

"The self-sacrifice of these comrades will forever remain etched in the collective memory of our nation," said Zuma.

"Theirs was a life well-lived, a life of struggle and a life dedicated to freedom, justice and democracy."

Sipho Hashe, Champion Galela and Qaqawuli Golozi were leaders of the Port Elizabeth Black Civic Organisation, known as Pebco, when they were abducted, tortured and killed by security police in Cradock in 1985.

Two members of the Congress of SA Students (Cosas), Sipho Mthimkulu and Topsy Madaka were killed in the same manner three years before.

"Whilst mourning, we must celebrate the heritage of freedom and justice that was bestowed upon us by these heroic South Africans and countless others," said Zuma.

Struggle songs were sung and a gospel choir sang at the four-hour service held at Nelson Mandela Metropolitan University Missionvale Campus.

The caskets, draped with South African flags were take to Zwide cemetery in Port Elizabeth.

The remains of the five were found on the farm near Cradock after a police officer gave testimony about his involvement in their deaths to the Truth and Reconciliation Commission.

Joining Zuma at the funeral were Rural Development minister Gugile Nkwinti, Correctional Services minister Nosiviwe Mapisa-Nqakula and her husband presidential political advisor Charles Nqakula.

Congress of the People leader Terror Lekota also present at the funeral.

On Sunday, Zuma is expected to attend the funeral of Zwelinzima Vavi's brother, David Thwani in Whittlesea next Queenstown.