The authorship of one of the world'smost famous press photographshas been called into question by the organisation that honoured it with "photo of the year" 50 years ago. Nick Ut won the World Press Photo award for the photograph known colloquially as "Napalm Girl", but officially titled The Terror Of War, in 1973. The striking image of anaked and terrified Kim Phucrunning away from a napalm attack became a symbol of the war's tragedy, and remains one of the most iconic photographs fromAmerica's war in Vietnam. World Press Photo announced on Friday, however, that it has "suspended its attribution" to Ut because of doubts over who actually took it. The body's report adds to the muddle over an issue that has split the photographic community since The Stringer, a movie released earlier this year, questioned Mr Ut's authorship. World Press Photo said its probe found that two other photographers – Nguyen Thanh Nghe, the subject of the film, and Huynh Cong Phuc – "may have been better positioned" to take the shot. "We conclude that the level of doubt is too significant to maintain the existing attribution," said Joumana El Zein Khoury, executive director of World Press Photo. "At the same time, lacking conclusive evidence pointing definitively to another photographer, we cannot reassign authorship, either." World Press Photo, an organisation whose awards are consideredinfluential in photography, won't attempt to recover the cash award given to Mr Ut, a spokeswoman said. Mr Ut's lawyer, James Hornstein, said his client hadn't spoken to World Press Photo after some initial contact before The Stringer was released. "It seems they had already made up their mind to punish Nick Ut from the start," he said. Gary Knight, a producer of The Stringer, is a four-time judge of the World Press Photo awards and a consultant to the World Press Photo Foundation. After two investigations, Associated Press (AP) – who Mr Ut worked for at the time – said it found no definitive evidence to warrant stripping Mr Ut's photo credit. The AP said it was possible Mr Ut took the picture, but the passage of time made it impossible to fully prove, and could find no evidence to prove anyone else did. On Friday, it said that its standards "require proof and certainty to remove a credit and we have found that it is impossible to prove exactly what happened that day on the road or in the (AP) bureau over 50 years ago." "We understand World Press Photo has taken different action based on the same available information, and that is their prerogative," the statement said. "There is no question over AP's ownership of the photo." Meanwhile, the Pulitzer Prize that Mr Ut was awarded for the photo appears to be safe. The Pulitzers depend on news agencies who enter the awards to determine authorship and Marjorie Miller, an administrator – and a former AP senior editor – pointed to the AP's study showing insufficient proof to withdraw credit. "The board does not anticipate future action at this time," she said on Friday. Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month with unlimited access to our award-winning website, exclusive app, money-saving offers and more.