Denis Goldberg, tried alongside Mandela and imprisoned for 22 years, dead at 87

South African anti-apartheid activist Denis Goldberg, who stood trial alongside Nelson Mandela in the 1963-64 Rivonia Trial and was imprisoned for 22 years by the regime, has died at the age of 87 at his home in Cape Town.

President Cyril Ramaphosa expressed his deep condolences at the passing of Goldberg, one of the most prominent white activists in South Africa's long struggle against racial repression.

"This is a moment for all of us to appreciate Denis Goldberg's brave dedication to our struggle and his lifelong activism in the interest of and in the physical presence of poor and vulnerable communities around our country," Ramaphosa said in a statement on Thursday.

"His revolutionary contribution reinforced the non-racial character of our struggle and of our democratic dispensation," the president said in a series of subsequent tweets.

Goldberg died on Wednesday after suffering from lung cancer for years, a member of his family said.

Goldberg, whose family had Lithuanian Jewish origins, was born in Cape Town in 1933.

A communist, he joined the African National Congress' (ANC) armed wing in 1961 to oppose the apartheid regime. He was arrested in 1963 at a clandestine meeting in a Johannesburg suburb and stood trial with several others, including Mandela and Walter Sisulu, in what became know as the Rivonia Trial.

He was convicted on sabotage charges and sentenced to life imprisonment after the judge declined to impose the death sentence.

Being white, Goldberg was not sent to the notorious Robben Island prison along with black political prisoners like Mandela, in keeping with the apartheid regime's philosophy that the country's different races should not mix.

Instead, he was jailed in the capital Pretoria, where he spent most of the time in solitary confinement.

He was released in 1985 after 22 years in prison after agreeing with the government not to take part in political violence. He continued his role in the anti-apartheid struggle from exile in London.

Apartheid ended with Mandela's victory in the country's first free elections in 1994, but Goldberg did not return to live there until 2002 due to family reasons.

In more recent years, Goldberg criticized failures by the now-ruling ANC to lift enough South Africans out of poverty. He was especially critical of former president Jacob Zuma, who faces several inquiries over corruption allegations during and before his time in office.

Mmusi Maimane, former South African opposition leader, and former British opposition leader Jeremy Corbyn were among those also paying tribute to Golberg on social media.