A photo of women shouting from a rooftop during protests after Iran's contested presidential election won the World Press Photo Award for Italian Pietro Masturzo.
AFP photographers Walter Astrada, Olivier Laban-Mattei and Mohamed Abed won the top three prizes in the spot news category. It is the second year running that Mr Astrada from Argentina has won the spot news award.
The black and white image by Mr Masturzo, a freelance photographer, was used to illustrate a story on how Iranians shouted their dissent from rooftops and balconies in the days after the June 12 election last year.
Iran's opposition has said the result was fixed to give President Mahmoud Ahmadinejad victory.
"The photo shows the beginning of something, the beginning of a huge story. It adds perspectives to news. It touches you both visually and emotionally, and my heart went out to it immediately," said Ayperi Karabuda Ecer, who headed the jury which chose the shot for the 2009 award.
"The photo has a powerful sense of atmosphere, tension, fear - but also of quietness and calm, and in this sense was a challenge as a choice," said Kate Edwards, a member of the jury.
"We were looking for an image that drew you in, took you deeper, made you think more - not just about showing what we already know, but something that asks more of us."
Mr Masturzo, 29, won one of the most prestigious international image awards after less than three years as a professional photographer. He will receive his €10,000 prize in Amsterdam on May 2.
The jury also gave a special mention to an image taken from a film put on the Youtube.com video sharing website which showed 26-year-old student Neda Agha-Soltan, who was shot dead during the Iran protests on June 20.
AFP photographers Mr Astrada, Mr Laban-Mattei and Mr Abed won their awards in the Spot News section for trouble-zone reporting.
Mr Astrada won first prize for a series of pictures of unrest in Madagascar in February 2009 during an uprising against President Marc Ravalomanana. Last year he won the award for picture of election violence in Kenya in 2008.
Mr Laban-Mattei won second prize for his images from the stormy Iran protests.
Mr Abed was selected for his reporting from the Israeli offensive against Gaza in January 2009.
Sixty-three photographers from 23 nationalities won prizes in 10 categories in the annual awards.
The 5,847 photographers who took part entered 101,960 photos.