Asmal was admitted to the Constantiaberg Medi Clinic on June 17 to treat a stomach ailment, but he died Wednesday after a serious heart attack, family spokesman Allan Taylor said in a statement.

He was born on October 8, 1934, in the eastern province of KwaZulu-Natal. While in high school, he met chief Albert Luthuli, then leader of the African National Congress and South Africa’s first Nobel Peace laureate.

Asmal later credited that encounter with inspiring him to activism. He began organising peaceful protests against apartheid even before graduating.

In 1959 he went to London to study law and later became a teacher at Trinity College in Dublin.

During his years abroad, he became a key leader of the British and Irish anti-apartheid movements, and only returned to South Africa in 1990 as the white-minority regime was teetering.

He was soon elected to the ANC’s national executive and became one of the negotiators in talks to end apartheid.

After Nelson Mandela became president in the first all-race elections in 1994, Asmal was appointed minister for water and forestry, later shifting to the education portfolio in 1999 under former president Thabo Mbeki.

In government, he was a rare voice unafraid to challenge the ANC line when he feared the party was falling short of its democratic ideals. At the time, he was rebuked for some of his stances, but after his death, the party hailed him as a giant of the struggle.

“He will be remembered for his energy, forthrightness, efficiency and commitment to making this country a better place each day. He will also always be remembered for his passion for human rights for all,” President Jacob Zuma said.

Just days before his hospitalisation last week, Asmal had publicly denounced a Protection of Information Bill backed by the ANC, calling it an “appalling measure” that would make it easier for the state to keep secrets from the public.

The bill has stalled in the ANC-dominated parliament.

In a March interview with AFP, Asmal explained his criticisms of the ruling party, saying he saw it as his role to speak out when the ANC failed to live up to its own founding principles.

“Those who have power now don’t have property rights over the African National Congress,” he said.

“They are there temporarily and therefore my own feelings have to be expressed because the soul of the ANC, the spirit of the ANC, the soul, the spirit, the foundation values of the ANC — and I am not being arrogant that only I, I know the foundation values — but the foundation values are there and if the foundation values are broken, there is a trespass against the foundation values, then there must be people who speak out against it.”

Zuma announced Thursday that Asmal would receive an official funeral, and declared a period of national mourning until the evening of his cremation — the date of which has not been announced.