Hugo photographed remnants of the Rwandan genocide which seemed to have seeped into the landscape for his book Rwanda: Vestiges of Genocide. Photograph: Pieter Hugo/Courtesy of Stevenon, Cape Town/Johannesburg and Yossi Milo, New York  A few weeks ago, Pieter Hugo won the Seydo Keita award, the most prestigious prize at the Rencontres de Bamako in Mali, Africa's foremost photography festival. I have been watching Hugo's progress intently since I interviewed him for the Observer in July 2008, having been astonished by the images in his book The Hyena and Other Men, which went on to become one of the most celebrated photobooks of the noughties.  I wrote then that the book would be a hard act to follow, but Hugo has gone his own way with a keen eye for harsh socio-political subject matter. In 2009, he published Nollywood, a series of staged portraits from the strange and often disturbing world of the Nigerian film industry, the third biggest in the world after Hollywood and Bollywood. Last year, he published Permanent Error, a dramatic evocation of the vast Agbogbloshie rubbish tip in Ghana, where most of the world's discarded computers end up. The workers there burn the computers in order to extract the valuable metals therein, a process that has turned the area into what looks like a post-apocalyptic landscape, where it is dangerous to breathe the air, drink the water or even dig up the soil for miles around. Like the Hyena Men of Nigeria, the workers here operate on the edge of society in a developing country that has – literally and metaphorically – become a dumping ground for the west's technological waste.  Hugo is not, though, a traditional social-documentary photographer or a straight portraitist. The men who pose for him in Permanent Error often strike an almost defiant look as if staring down the camera, or daring it to pass judgment. At Paris Photo last week, a couple of these portraits were printed at almost life size. They were strangely beautiful pictures that tell of immense suffering, but speak also of human endeavour and dignity.  Now, Hugo has released a book of older work in limited edition on a small English imprint, Oodee: Rwanda 2004 Vestiges of a Genocide. It features an essay by an investigative journalist, Linda Melvern, who has written extensively on Rwanda. The book is a powerfully restrained piece of work that began when Hugo came across an article in a financial magazine about Rwanda's development since the genocide of 1994, when nearly a million people were murdered in an "organised and efficient" campaign by Hutu groups.  Hugo was astonished to see, accompanying the article, a photograph of a human skull on a church altar. "The photograph was captioned 2004, 10 years after the genocide. According to the journalist, there was detritus from the genocide everywhere. This sparked a series of questions. Why had nobody cleaned it up yet? Why were there no international commemorations? How does one regard landscape where this type of atrocity has occurred?"  The last question most informs the book and guided Hugo's way of seeing and presenting what he saw. There are photographs of human skulls – as well as bones and bodies covered in lime – in the book, but there are also images of landscapes where unspeakably bad things happened: a banana plantation, a rural football field, a view over serene Lake Kivu. The accompanying captions hint at the full horror lying latent in these seemingly innocent places: "Those who tried to hide in plantations were hunted down"; "Once in the (soccer) stadium, no one was allowed to leave … the massacre began on 18 April, with grenades thrown into the crowds"; "an unaccountable number of people were drowned in rivers and lakes which were also used to dump rotting bodies".  Here, it is the lingering remnants of the genocide that shock, and the sense that what happened has literally seeped into the landscape and into the collective psyche of the people.  When I interviewed Hugo in 2009, he said he was drawn to "that which we do not want to look at", while also acknowledging that he had "a deep suspicion of photography, to the point where I sometimes think it cannot accurately portray anything, really." He has been grappling with that paradox ever since, making work that is formally rigorous and often provocatively powerful. As the Seydo Kieta prize recognises, he relentlessly questions the power of photography though his dramatic and unsettling images.  At Brancolini Grimaldi, London, the veteran Italian photographer Massimo Vitali shows a new series of sparsely populated coastal landscapes that provides a counterpoint to his better-known panoramas of his homeland's crowded beaches and resorts. His vision remains epic, but in these large-scale prints humans are dwarfed by rocks, cliffs and quarries. From 18 November 2011 to 28 January.
Sean O'Hagan: The still-visible aftermath of the 1994 atrocities forms the focus of one of Hugo's projects, in which he challenges the camera's power to portray things as they really are