Nadine Gordimer: Author and activist whose novels interweaved the personal and the political in her accounts of apartheid South Africa

Nadine Gordimer won the 1991 Nobel Prize for Literature for morally complex novels that explored the cost of racial conflict in apartheid-era South Africa, tightly interweaving personal and public passions. As a white South African who hated apartheid, she also played a political role in her country's troubled history.

She was born near Springs, a mining town near Johannesburg. Her father, Isidore, was a Latvian watchmaker, while her mother, Hannah, or Nan, was from a London family of Jewish origins, although Nadine was raised in a secular household. Her father had been a refugee from tsarist Russia – although, Nadine noted, his experiences gave him no particular feeling for those oppressed under apartheid.

Her mother did, however, and opened a crèche for black children. Political awareness came early: when Nadine was in her teens the police raided the family home, taking letters and diaries from a servant's room. She was educated at a Catholic convent school, though she was often kept at home by her mother, apparently because she feared she had a weak heart. Gordimer published her first stories for children when she was 15: "The Quest for Seen Gold" appeared in the Children's Sunday Express, while "Come Again Tomorrow" appeared in a magazine.

Gordimer studied at the University of the Witwatersrand, mixing for the first time with fellow professionals across the colour bar. Leaving after a year, she moved to Johannesburg where, while taking classes, she continued writing – stories she collected in Face to Face, published in 1949, just after apartheid had become state policy. Two years later New Yorker accepted her story "A Watcher of the Dead" – the start of a long and fruitful relationship with the magazine.

Her first publisher, Lulu Friedman, was the wife of the United Party MP Bernard Friedman – who later co-founded the Progressive Party – and it was at their house in Johannesburg that Gordimer met other anti-apartheid writers. Her first novel, The Lying Days, a Bildungsroman charting the growing political awareness of a young woman, came out in 1953, and the following year she married the art dealer Reinhold Cassirer (she had already married and divorced a dentist, Gerald Gavron) . Their son, Hugo, is a film-maker in New York.

Her political consciousness was sharpened in 1960 when her best friend, the campaigner Bettie du Toit, was arrested and the Sharpeville massacre shocked the world. She became close friends with Nelson Mandela's defence lawyers, Bram Fischer and George Bizos, during his trial in 1962, and she helped Mandela edit the "I Am Prepared To Die" speech that made him a global cause célèbre. When he was released from prison in 1990, Gordimer was one of the first people he wanted to see. She later recalled that after he was established in Johannesburg, often alone in his big house at night, he would call her and invite himself to dinner.

Leaving for short periods to teach at US universities, she began to achieve international recognition. The South African government banned several books – The Late Bourgeois World for a decade, A World of Strangers for 12. She joined the ANC and hid ANC leaders in her home; she said the proudest day of her life was when she testified at the 1986 Delmas Treason Trial on behalf of 22 activists.

In 1974 she shared the Booker Prize with Stanley Middleton for The Conservationist, which explores Zulu culture and the world of a wealthy white industrialist. One of her best-known books was Burger's Daughter (1979), in which a woman analyses her relationship with her father, an anti-apartheid martyr, and is drawn into activism. Written in the aftermath of the Soweto uprising, it was another of her books to be banned; she described it as a "coded homage" to Mandela's lawyer Bram Fischer.

In 1991 she was awarded the Nobel Prize. The Nobel committee's citation observed: "Gordimer writes with intense immediacy about the extremely complicated personal and social relationships in her environment." In her acceptance speech she said that as a young artist she had agonised that she was cut off from "the world of ideas" by the isolation of apartheid. But she came to understand "that what we had to do to find the world was to enter our own world fully, first. We had to enter through the tragedy of our own particular place".

Her activism was wide-ranging: in the post-apartheid era she was active in the HIV/Aids movement, and in 2004 she gathered around 20 well-known writers to contribute stories to Telling Tales, a fund-raising book for South Africa's Treatment Action Campaign. She was critical of the government's stance, and said she approved of everything President Thabo Mbeki had done except his stance on Aids. In 2001 she urged her friend Susan Sontag not to accept an award from the Israeli government, though she angered some by refusing to equate Zionism with apartheid. In 1998 she refused to be shortlisted for what was then the Orange Prize, because it was open only to women.

Her final novel, No Time Like The Present (2012), follows the fortunes of a family and their friends in a Johannesburg suburb between the mid-1990s and 2009. In The Independent, Boyd Tonkin wrote, "With her impacted syntax and unsettling, even opaque, diction, late-period Gordimer can test the reader as much as late Henry James. Yet at best her free-style, high-velocity storytelling delivers a visceral immediacy and intensity that lets us inhabit the minds, and share the views, of her characters with the minimum of novelistic fuss."

Her close friend Per Wastberg, a fellow author and a member of the Nobel Prize committee, said her descriptions of the different faces of racism told the world about South Africa during apartheid. "She concentrated on individuals, she portrayed humans of all kinds," he said. "Many South African authors and artists went into exile, but she felt she had to be a witness to what was going on and also lend her voice to the black, silenced authors."

Nadine Gordimer, author: born Springs, South Africa 20 November 1923; married 1949 Gerald Gavron (marriage dissolved; one daughter), 1954 Reinhold Cassirer (died 2001; one son); Nobel Prize for Literature 1991; died Johannesburg 13 July 2014.