Virginia Republican Senator John Warner, chairman of the Senate armed services committee, raised the issue at a hearing with Rumsfeld and top US generals on Thursday after receiving letters from Reuters and the Committee to Protect Journalists (CPJ).
Warner had also received a similar complaint from Paul Steiger, CPJ chairman and managing editor of The Wall Street Journal.
"I raised the question of the safety of the press in Iraq and their ability to carry out the very important function of reporting to the American people," Warner told reporters after the hearing.
"I've discussed it with the secretary. He's going to take it under immediate consideration," he said.
Abuse of power?
In a letter to Warner earlier this week, Reuters Global Managing Editor David Schlesinger referred to "a long parade of disturbing incidents whereby professional journalists have been killed, wrongfully detained, and/or illegally abused by US forces in Iraq".
At least 66 journalists have been
killed in Iraq since March 2003
He urged Warner to demand that Rumsfeld address and resolve these issues "in a way that best balances the legitimate security interests of the US forces in Iraq and the equally legitimate rights of journalists in conflict zones under international law".
Responding to Warner during the hearing, General George Casey, the top US commander in Iraq, said: "It's an issue that we take very seriously. And what I will do when I get back to Baghdad is I'll get a few of the local journalists together and work through some of their concerns with them."
Warner responded that the Pentagon should go further by directly communicating with the media organisations that had written to him, as well as convening a representative group of reporters in Iraq to get their views.
At least 66 journalists and media workers, most of them Iraqis, have been killed covering Iraq since March 2003. US forces acknowledge killing three Reuters journalists, most recently soundman Waleed Khaled who was shot by American
soldiers on 28 August while on assignment in Baghdad.
But the military say the soldiers were justified in opening fire. Reuters also believes a fourth journalist who died in Ramadi last year while working for the agency was killed by a US sniper.
"They [US soldiers] threaten to undermine the ability of the media to report on events in Iraq, especially as international news organisations rely heavily on Iraqi journalists to work in frontline newsgathering"
CPJ executive director
In a letter to Rumsfeld sent on Wednesday, CPJ executive director Ann Cooper said the indefinite detention of reporters in Iraq on unsubstantiated evidence was an unacceptable interference in the work of media professionals.
"They threaten to undermine the ability of the media to report on events in Iraq, especially as international news organisations rely heavily on Iraqi journalists to work in frontline newsgathering," she said.
At least seven Iraqi journalists were detained this year, with at least three documented detentions lasting more than 100 days while others spanned many weeks, the New York-based group said in a letter to Rumsfeld on Wednesday.
At least four detainees remain in US custody, including three Reuters employees and one from CBS News. Additionally, the arrests sent the message to Iraq that the US commitment to democracy and human rights was not sincere.
Schlesinger said the US military had refused to conduct independent and transparent investigations into the deaths of the Reuters journalists, relying instead on inquiries by officers from the units responsible who had exonerated their soldiers.