The International Committee of the Red Cross (ICRC) has called on both sides of the Iraq war to take more care to stop ordinary people from becoming victims.
The US is investigating claims of mass deaths in Hilla
Florian Westphal, the international humanitarian group's spokesman, said: "We would once again urgently remind all the parties in this conflict of their absolute obligation to do everything to protect civilians - in the way they are fighting and the way they choose their targets."
He said ICRC workers saw "dozens" of bodies arriving at the Hilla hospital in central Iraq, some apparently the victims of warfare; US helicopter gunships strafed a nearby residential area on Tuesday.
The demands came as Iraqi officials and US soldiers blamed each other for the deaths of 250 civilians in Nasiriya since the war started.
Doctors at the Saddam Hospital also said more than 1,000 people had been injured, mostly in the US air strikes.
But a commander of the US marines in the area blamed the tactics of the Iraqi militia and regular troops for the heavy casualties that the civilian population appear to have suffered.
Colonel Ron Johnson said civilian casualties had been inevitable because the Fedayeen militia and the Iraqi army had ignored the rules of war.
He admitted some schools had been attacked because Iraqi forces had been inside, and accused the Iraqis of also using hospitals and mosques as cover.
The BBC's Andrew North reports seeing large numbers of injured civilians at the hospital.
He was also shown books registering more than 250 deaths at the hospital over the past 11 days, but says it was impossible to check the doctors' claim that all those listed were civilians, or that most had died as a result of American air strikes.
He says it is possible at least some of the deaths were Iraqi irregulars, but the doctors insisted all military personnel had been treated elsewhere.
Fears of more civilian carnage were raised on Wednesday with reports that a maternity hospital in Baghdad had been hit by a bomb.
The ICRC - which runs the hospital - later confirmed that the hospital had been damaged though it was empty at the time and no-one died inside.
Other reports, however, say that some passers-by outside the building were killed.
US commanders were investigating the targeting of bombs around the Iraqi capital, but stressed that they go to "great lengths to minimise civilian casualties and damage to civilian facilities".
Iraqi authorities said on Wednesday that at least 55 civilians had been killed by coalition forces in attacks on Baghdad and other cities in the past 24 hours.
BBC defence analyst Stephen Dalziel says the US-led forces have gone out of their way to try to show that this war is against the regime of Saddam Hussein, not the Iraqi people.
He says inevitably, though, there have been civilian casualties and in a war being fought under the constant gaze of television cameras, both sides have realised how crucial the propaganda war is.
The United States has admitted shooting dead seven women and children after their vehicle failed to stop at a checkpoint in Najaf on Monday, but said "the climate established by the Iraqi regime" had contributed to the incident.
The human rights organisation, Amnesty International has called on Washington to conduct an independent investigation into the Najaf killings.