The Observer's 20 photographs of the week

The best photojournalism this week came from Africa, from events honouring the life of Nelson Mandela, and from the violence in the Central African Republic. Here, in this photograph by Ben Curtis, young members of a choir attend a morning mass in memory of Mandela at the Regina Mundi church in Soweto, Johannesburg Photograph: Ben Curtis/AP

The hearse carrying the body of the former South African president Nelson Mandela passes mourners in Pretoria Photograph: Muhammed Muheisen/AP

A woman looks out of a dusty window after boarding a bus to be transported to see the casket of Nelson Mandela at the Union Buildings in Pretoria Photograph: Markus Schreiber/AP

Roberto Schmidt's now infamous photograph of David Cameron, the Danish prime minister Helle Thorning Schmidt and Barack Obama taking a 'selfie' during the Nelson Mandela memorial service in Johannesburg. The photographer wrote in a blog: 'I thought the world leaders were simply acting like human beings, like me and you. I doubt anyone could have remained totally stony faced for the duration of the ceremony, while tens of thousands of people were celebrating in the stadium. For me, the behaviour of these leaders in snapping a selfie seems perfectly natural.' Photograph: Roberto Schmidt/AFP

An irritated Kodiak bear snaps at a wasp buzzing persistently around its head at Buffalo zoo, New York Photograph: Terry Cervi/Caters News

A mounted Israeli police officer disperses a protest by ultra-Orthodox Jews outside a military prison near the northern city of Haifa, in Israel. A police spokesman said that about 1,000 people took part in the protest against the jailing of Jewish students who failed to comply with a conscription notice Photograph: Nir Elias/Reuters

The changing of the guards ceremony at the tomb of the unknown soldier in Athens Photograph: John Kolesidis/Reuters

Drug users gather beneath an overpass in an area known as 'Cracolandia', in the Antares shantytown in Rio de Janeiro, Brazil. According to the Economist magazine, recent studies have shown Brazil to be the world's largest market for crack cocaine, with up to 1.2m users Photograph: Mario Tama/Getty

A riot policeman in Cairo looks out as student supporters of the Muslim Brotherhood throw fireworks during a protest outside the University of Cairo campus Photograph: Mahmoud Khaled/AFP

A diver swims underwater at Ginnie springs in High springs, Florida Photograph: Ocala Star-Banner/Landov/Barcroft Media

A tiger shark is photographed while being fed by divers, off Tiger beach, in the Bahamas Photograph: Daniel Botelho/Barcroft Media

A man carries a wounded girl who survived what activists say was an air strike by forces loyal to Syrian president Bashar al-Assad, in the northern city of Aleppo Photograph: Reuters

Jang Song Thaek, the uncle of the North Korean leader Kim Jong Un, is escorted into court with his hands tied, in this image released by Yonhap News Agency. It was later announced that Jang, previously viewed as the second most powerful figure in the country, had been executed for treason Photograph: Yonhap/Reuters

North Korean commuters gather around a newspaper stand on a train platform in Pyongyang to read about the execution of Jang Song Thaek Photograph: David Guttenfelder/AP

Fog envelops the business district of Canary Wharf in east London, with the City of London in the distance, in an image captured by a member of the Metropolitan Police service air support unit Photograph: Metropolitan Police/PA

A pair of spotted tiger beetles photographed while mating, on the banks of Jayanti river in the Buxa National Park in Alipurduar, India Photograph: Arkaprava Ghosh/Barcroft India

Photographer Thomas Senf used coloured flares and spotlights to produce this dramatic image of climbers Daniel Arnold and Stephan Siegrist on the Eidfjord in northern Norway Photograph: Thomas Senf/Mammut/Photopress/AP

AFP photographer Fred Dufour continued his excellent photojournalism from the unrest in the Central African Republic. Here, children ask for biscuits at a camp run by the French military in Bossembele Photograph: Fred Dufour/AFP

People dig graves to bury 16 coffins in a Muslim cemetery in the PK16 district of Bangui, in the Central African Republic. The father of a slain French soldier has described how disarmed Muslim fighters were lynched by a Christian mob, offering harrowing testimony that raised fears of a new wave of sectarian killing in the country Photograph: Fred Dufour/AFP

And in this final photograph by Fred Dufour, a young woman holds her baby at a school in the Muslim district of Bangui Photograph: Fred Dufour/AFP