Enzo Baldoni is "motivated by humanitarian feelings for the world's suffering people. He is an independent journalist and is totally autonomous", the director of the weekly Diario, for which Baldoni was on assignment, said in the statement on Tuesday.
"We are counting on this explanation to show who Baldoni was, someone who had nothing to do with the policies of the Italian government and who found time to carry out humanitarian acts - this should facilitate his release," a source at the magazine said.
To illustrate Baldoni's humanitarian instincts, the Diario video was accompanied by photos of an Iraqi man whom the journalist assisted after he was wounded by a US tank.
It also detailed Baldoni's crucial role in the delivery by the Italian Red Cross of two shipments of humanitarian aid to the besieged city of Najaf, once on 15 August and again on 19 August.
Baldoni's captors, a group calling itself the Islamic Army in Iraq, released video footage earlier on Tuesday of the journalist, urging Italy to withdraw its 3000 troops from Iraq. Baldoni disappeared last week on the road to Najaf.
Rome immediately vowed that its troops would remain in Iraq. The group did not specify the consequences of a failure to comply, saying only that "it cannot guarantee the Italian's safety," Aljazeera reported.
Diario is known in Italy for the rigour of its investigative reporting and its independent tone, and is generally critical of the administration of Italian Prime Minister Silvio Berlusconi and its support of the US-led war.