Jorge Semprun: Novelist who survived Buchenwald and was later a member of the anti-Franco resistance

There is little doubt that Jorge Semprún, one of Spain's most influential writers of the 20th century, appreciated the importance of words:an intentional typing error of a single letter by an anonymous German civil servant when he was sent to Buchenwald concentration camp saved his life.

The error was enough to change the description of Semprún's status from student to craftsman: the first were regularly assigned to the most dangerous and exhausting jobs from which there was no return; the second far more likely to survive.

However, the atrocities committed in Buchenwald had an indelible, lifelong, impact on Semprún's writing, because as he so devastatingly once put it: "What do you do with the memory of the smell of burning flesh? "It is the most important smell of a concentration camp and I cannot explain it, it is just there with me." And in his writing, even as late as the 1990s, there it remained.

Semprún was born in Madrid in 1923 into a well-off middle-class home;his maternal grandfather was Antonio Maura, a political chameleon and free-thinker who was five times Spanish president, while his father, Jose María, was an ambassador for the Spanish Republic to the Netherlands: as a result Semprún spent much of his childhood abroad.

When Franco's forces took Madrid in 1939, that exile – in Paris – forcibly became permanent. Semprún studied at the Sorbonne before joining the Spanish Communist Party (PCE) in France and then the French resistance movement in 1942. Caught and tortured by the Gestapo in 1943, Semprún spent two years in Buchenwald. His "job" there as a statistician partly consisted of rubbing out dead prisoners' names and reassigning their numbers to fresh arrivals.

But while he was acutely aware that as a writer he had a moral obligation to pass on those sorts of macabre experiences from his concentration camp life to future generations, it took Semprún nearly 20 years to come to terms with them. "I could not do so any sooner" he once said, "because I would have committed suicide."

Following the camp's liberation, Semprún returned to Paris to work as a translator for Unesco, but his political commitments remained strong and for nearly a decade from 1953 onwards he formed part of the PCE's underground resistance to Franco's regime, becoming a member of the executive committee in 1956. Like Buchenwald, his clandestine years in Madrid marked him deeply.

"Years later, whenever I went to lunch with somebody, I would always wheel round just before the meeting place to check I was not being followed," he recalled in one of his last interviews, "then I would burst out laughing at myself."

His memories of that period found their way into a novel, The Autobiography of Federico Sanchez (1977), and so, too, did his expulsion from the PCE in 1964, following his falling-out with the long-standing leader Santiago Carrillo, and the party's Stalinist line.

Semprún could not fail to notice, for example, that post-liberation Buchenwald had promptly been converted into a holding camp for East German political prisoners – something that reinforced his belief "better the capitalist jungle rather than the totalitarian zoo".

Deeply disillusioned with political life, although he remained strongly committed to left-wing causes, Semprún returned to France and began writing in earnest, with his first novel, The Long Voyage (aka The Cattle Truck) published in 1963. An account of a five-day journey by a resistance fighter towards Buchenwald, it was the first of several semi-autobiographical works centred around concentration camp life, most notably Quel Beau Dimanche (1980) and Writing and Life (1994) that spanned three decades of writing.

Apart from his novels, Semprún's prolific output included 15 screenplays, mostly politically orientated andincluding two Oscar-nominatedproductions, La Guerre est Finie (1966) and Costa-Gavras's hugely successful political thriller Z (1969), as well asanother film by the same director,the strongly anti-Stalinist The Confession (1970).

Although Semprún wrote mainly in French, and spent most of his later life in France, he remained a Spanish national – a choice which was to cost him, not without controversy, a place in the Académie Francaise, although he later became the first non-French member of the Académie Goncourt.

Probably the most important consequence of remaining Spanish, though, came in 1988 when Semprún received a phone call at two in the morning from the future Nato Secretary-General and the then Socialist government spokesman, Javier Solana, asking him if he still held a Spanish identity card, and if so then would he like to become Spanish Minister of Culture?

He accepted, but despite successfully handling the negotiations with Baron Thyssen for the opening of his museum, as well as Dali's artistic legacy, Semprún unwisely made an enemy of the formidable vice-president, Alfonso Guerra. In 1991, Semprún left his post, with his novel Goodbye from Federico Sánchez (1993), an account of his time – and tribulations – there.

Upon his death, tributes from politicians flooded in from both sides of the Pyrenees, with the French president Nicolas Sarkozy describing him as "someone who made a decisive contribution to the understanding of totalitarianism", while Sarkozy's Spanish counterpart Jose Luis Zapatero called him "a militant for freedom, culture and thought".

Rather than any country, though, Buchenwald, was Semprún's spiritual homeland as a writer, as he obliquely hinted in April last year when he made his last trip back to the camp, for the 65th anniversary of its liberation. Standing in the camp's central Appelplatz square, he made a speech that recalled the "wonderful historical irony" that the two first American solders to reach Buchenwald (a later arrival that day was Barack Obama's great-uncle) were Jewish, and then described the transportation there of former Auschwitz inmates close to the end of the war, in appalling physical conditions.

Last of all Semprún remembered himself as a 22-year-old, carrying an anti-tank bazooka and celebrating "with gestures of furious happiness" the Americans' arrival in a place he called "the final frontier... of dreams maintained against all the odds." And perhaps that combination of flickering, youthful hope amid so much tragedy is the most appropriate image with which to remember him.

Jorge Semprún, writer and political activist: born Madrid 10 December 1923; married 1947 Loleh Bellon (marriage dissolved, died 1999; one son), 1963 Colette Leloup (died 2007; three sons, two daughters); died Paris 7 June 2011.