Soweto, South Africa — US television celebrity Oprah Winfrey on Thursday paid emotional tribute to Nelson Mandela as she prepared to host a star-studded concert in Johannesburg to cap celebrations marking 100 years since his birth.

Winfrey will co-host the Global Citizen festival on Sunday, where artists including Beyonce, Jay-Z, Cassper Nyovest, Ed Sheeran, Femi Kuti, Pharrell Williams, Chris Martin and Tiwa Savage will perform.

The concert is the climax of a year of events celebrating the centennial of Mandela's birth in 1918, and is part of a campaign to tackle poverty, child malnutrition and boost gender equality.

Winfrey hailed Mandela's "goodness and integrity", describing him as her "favourite mentor" as she spoke at a public debate at the Soweto campus of the University of Johannesburg.

"He was a man who could have sought revenge, but he was a man who sought reconciliation," she said, adding he "knew that when one of us is wounded all of us are bleeding."

Mandela was jailed under South Africa's apartheid regime. After being released in 1990, he led the country's transformation into a multi-racial democracy. He died on December 5, 2013 aged 95.

She said Mandela "could have actually crushed his opponents with his power but instead he choose to defeat them without ever" ever disarming them.

Former US president Barack Obama spoke in Johannesburg in July, delivering the flagship address of the "Mandela 100" celebrations, remembering the "wave of hope that washed through hearts all around the world" when Mandela was released from jail.

Tickets for the weekend concert were allocated to people who have taken part in the Global Citizen campaign.

The 64-year-old talk show queen spoke to hundreds of mainly women guests at an auditorium in Soweto, a township which was the hotbed of the struggle against apartheid. — AFP