Images of redemption: John Keane in Angola

Still-lifes and posed portraits are not John Keane's stock in trade. It is conflict that gets this artist's creative juices flowing. From the Falklands to the Gulf War, he has brought political violence alive on the canvas time and again. But for his latest exhibition, the war artist has chosen to focus on what happens when the fighting is over.

His subject is Angola, the oil-rich southern African country soon to mark its sixth year of peace after being ripped apart by a bloody civil war. For almost three decades, the battle raged; hundreds of thousands of people died, hundreds of thousands of others fled their homes.

Peace is now firmly in place, with the country's first presidential elections since 1992 due next year, but the scars still run deep – be they the still-buried landmines, the bullet-riddled and half-ruined schoolrooms, or the psychological trauma suffered by an entire generation of children.

These hardly sound like the ingredients for uplifting art, but in Keane's hands the optimism of Angola shines through. The colours are vibrant, the faces empathetic, and the political messages compelling. "I've attempted to evoke the huge tasks of reconstruction and reconciliation in the face of enormous odds, but at the same time allude to the indomitable optimism of the human spirit I encountered in the new generation of post-war Angolans," Keane says.

Researching the series of 11 paintings, commissioned by the British charity Christian Aid, took Keane into uncharted territory – literally, when he accompanied a de-mining team to Cuando Cubango, the region that Angolans dub "the province at the end of the world", which witnessed some of the civil war's fiercest fighting.

He incorporated this legacy of the war in his work by weaving the Portuguese warning "Perigo Minas" ("Danger: Mines") into fabric worn by his figures. "It's subliminal. You won't see it unless you scan very carefully. It's rather like the hidden aspect of landmines," he explains.

His two-week field trip to Angola introduced him to children who had fled into the bush and had missed out on their schooling, brothers who had fought for opposing factions in the civil war, people struggling to survive despite the country's oil bonanza. "To me it was literally a blank canvas. I wanted to act like blotting paper and absorb as much as possible," he says.

Back in his London studio, Keane spent a year paring down hundreds of digital photos, before constructing his paintings with a mixture of collage, fabric printing and oil paint. The resulting images are almost photographic in their detail, but they have been subtly manipulated to include social commentary about corruption, exploitation and the lasting repercussions of war; there's no denying the political punch they pack. "I don't want to be preachy or bash people over the head with it," Keane says. "But I hope there's a redemptive quality that seeps through without people realising it."

John Keane: Angola, Flowers Central, Cork Street, London W1 (020-7439 7766) today to 29 March

Bridge

Hundreds of thousands of refugees fled Angola for the safety of Zambia, among them 14-year-old Florinda, the subject of Keane's "Bridge" painting. Her father was killed as the family tried to escape the conflict. Now that a lasting peace has allowed them to return home, Florinda and her surviving relatives are trying to rebuild their lives. On his field trip, the artist witnessed these families receiving starter kits including scythes, blankets and vivid green buckets. "It's difficult for us to comprehend that something so simple and basic can create such excitement," Keane explains. By bleaching the colours in the rest of the painting, it is the green, almost overflowing bucket, that seizes the viewer's attention, borne by a girl who's never had the chance to go to school. "As the eldest child, the responsibility is on her shoulders, or in this case on her head," Keane muses.

Arsenal

Keane is a man fond of coincidences, so when he spotted an Angolan boy wearing the football shirt of his local team – albeit a dusty and incredibly out-of-date one – he knew that he would have to incorporate it into a painting. He describes "Arsenal" as a standing metaphor of how children's education suffered during the war years. The schoolroom is based on one he saw in a remote village, its walls riddled with bullet holes but also the doodlings of idle children, the building in ruins but white chalk writing still discernible on the blackboard. "The classroom has been neglected all these years and it's going to take a lot of rebuilding," Keane reflects. In the meantime, the skeleton building attracts children with their spinning tops, home-made wire toys and deflated footballs. But there is no doubting the thirst for education in Angola. Keane spent time at another village where every resident had turned out to build a basic thatched-roof schoolroom, and another hamlet where children clocked up a 20km walk every day just to get to classes.

Brothers

Angola's civil war ripped families in two, and thrust brothers Amaral (left) and Luis (right) Samacumbi on to opposite sides after both were conscripted against their will. Reunited after the war ended in 2002, they made the chilling discovery that they had actually fought against each other in the same battle. "It could have happened that I killed my brother," Luis recalls with a shudder. Keane again plays with African fabrics to impart his impressions of post-conflict Angola, personalising the vibrant, eye-catching patterns with bleaker images. The yellow and green landmines repeated around Amaral pay a poignant tribute to the limbs that he and thousands of others lost in the war.

Shanty

During his days in the Angolan capital, Luanda, Keane was struck by the new brand of refugees, ousted from their homes not by war but by commercial interests. Many residents in the makeshift shanty towns say they lost their land to property developers wanting to cash in on the new-found peace in Africa's second biggest oil producer. The poverty in the painting is inescapable. The canvas is dominated by the shack, cobbled together from corrugated iron and plastic sheeting. There's a discreet nod to the encroaching powers of capitalism, with a mobile phone tucked into the mother's skirt, but for the real wealth you have to look a bit closer – at that same skirt. The pattern may look like a traditional African one, but it is in fact made up of repeated silhouettes of oil rigs and an Angolan kwanza banknote.