Dana was an experienced conflict journalist
US troops must account for their killing of Reuters cameraman Mazen Dana in Iraq on Sunday, the news agency's Chief Executive Tom Glocer has said.
Mr Glocer said "it seemed quite incredible" that US troops could have mistaken Mr Mazen's camera for a rocket-propelled grenade launcher - the explanation given for the incident.
He said a full inquiry into the incident was necessary because the Iraq conflict had been the bloodiest war against journalists, with 17 killed - including Mr Dana and another Reuters cameraman - either during or after the conflict.
International media rights bodies, the New York-based Committee to Protect Journalists (CPJ) and Reporters sans frontieres (Reporters Without Borders, RSF) in Paris, have also called on the US to launch a full inquiry.
"All of us who have seen what a shoulder-held television camera looks like, it is a different-looking beast certainly during the afternoon sunlight. One should be able to tell from 50 yards away," Mr Glocer told the BBC Radio 4's Today programme.
"But again in conditions of war, young soldiers fearing for their own lives don't have a lot of time to make fine distinctions."
The shooting happened at Abu Ghraib prison, west of Baghdad, where six Iraqis were killed in a mortar attack late on Saturday.
His death brings to 19 the number of journalists and their assistants who have died in Iraq or have gone missing since the conflict began.
The incident took place in daylight on Sunday afternoon.
Mr Dana and his sound engineer had asked permission to film from US soldiers near the prison shortly before the incident.
But shots were later fired from a US tank, and the cameraman was hit in the chest.
He was taken to a US military hospital but pronounced dead on arrival.
Mr Dana is the second Reuters cameraman to be killed since US-led troops invaded Iraq.
In April, Reuters cameraman Taras Protsyuk, a Ukrainian based in Warsaw, died when a US tank fired a shell at the Palestine Hotel, the base for many foreign media in Baghdad.