An exhibition of the winning entries, which went on show at the Southbank Centre in London today showcases the best in photojournalism from across the globe and features startling pictures from the world in 2011.
This year's top prize was awarded to Spanish photographer Samuel Aranda for his image of a mother cradling her son in her hands after he has been overcome by tear gas during an anti-government demonstration in Yemen.

Tragic: This work by Brent Stirton won first prize in the Contemporary Issues Singles category. it shows Maria, a drug-addicted sex worker, resting between clients in the room she rents in Kryvyi Rih, Ukraine. The country has the highest incidence of HIV/Aids in Europe, according to UNICEF
Comment: Read Part 1: Psychiatric Drugs and War: A suicide mission