Thirty-six journalists were killed as a direct result of their work in 2003, with the US-led war in Iraq accounting for more than a third of the casualties, according to the New York-based Committee to Protect Journalists.
Thirteen journalists were killed in Iraq during hostile actions, CPJ said. Six others who died from illness or traffic accidents while covering the war were not included in the total.
In 2002, 19 journalists were killed worldwide.
The death toll in Iraq was the highest from a single country since 24 journalists were killed in Algeria in 1995 during civil strife between the government and Islamist militants, CPJ said.
"The war that began in March posed many hazards for journalists, but seasoned war correspondents tell us that even in the postwar period Iraq remains the most dangerous assignment they have ever had," CPJ Executive Director Ms Ann Cooper said in a statement.
She added that "it has been particularly troubling to see at least four journalists killed as a result of US military actions in Iraq, and CPJ continues to demand a full public accounting from the Pentagon for these incidents."
In the Middle East's other major conflict, two journalists were killed by Israeli army gunfire in the West Bank and Gaza Strip, bringing to six the number of journalists killed since a Palestinian uprising began in 2000.
Nearly all the journalists killed outside Iraq were deliberately targeted, often in reprisal for their critical reporting, according to CPJ.
In the Philippines, five journalists were killed for covering local corruption or criticizing public officials. In Colombia, three journalists were murdered because of their work and one was killed in cross-fire. And in Russia, the editor of an independent publication known for its reporting on organized crime and corruption was stabbed to death outside his home.
CPJ said it is still investigating four journalists who are missing and 12 whose killings may have been related to their professional work.