JOHANNESBURG: South African anti-apartheid figure Andrew Mlangeni, who stood trial alongside Nelson Mandela in the 1963-64 Rivonia Trial, has died at the age of 95, the presidency announced on Wednesday.

Mlangeni, 95, was the last surviving Rivonia trialist, spending more than quarter of a century imprisoned on Cape Town's notorious Robben island before his release in 1989.

"President Cyril Ramaphosa has learnt with deep sadness of the passing away overnight of the last remaining Rivonia Trialist," the presidency said in a tweet.

His death "signifies the end of a generational history and places our future squarely in our hands," he declared. Mlangeni was admitted to a military hospital in the capital Pretoria on Tuesday with an abdominal complaint, the presidency said.

Hailing Mlangeni as a "principled and modest" man, the Desmond & Leah Tutu Legacy Foundation said his passing "sounds the last post on a courageous generation of South Africans."

"He is deeply mourned," the foundation said in a statement.

Born in the Johannesburg township of Soweto, he joined the youth wing of the African National Congress (ANC) in the early 1950s.

In the early 1960s, he was among the first groups of liberation fighters to be sent outside of South Africa for military training.

When he returned two years later, he was arrested.

The eight-month Rivonia Trial, named after the Johannesburg suburb where the ANC leaders were arrested, brought the struggle against apartheid to world attention. Expecting to be sentenced to death, Mandela declared in a three-hour speech from the dock that freedom was "an ideal for which I am prepared to die."