A controversial new study contends nearly 655,000 Iraqis have died because of the war, suggesting a far higher death toll than other estimates.
The timing of the survey's release, just a few weeks before the U.S. congressional elections, led one expert to call it "politics."
Within hours, President Bush dismissed the study.
Mr. Bush told reporters at a White House news conference: "I don't consider it a credible report."
"Neither does General Casey, neither do Iraqi officials," Mr. Bush added, referring to Gen. George Casey, the top U.S. general in Iraq.
Mr. Bush, who last December suggested there may have been 30,000 civilian deaths in Iraq, would not give a figure Wednesday for overall fatalities. "A lot of innocent people have lost their life," he said.
In the new study, researchers attempt to calculate how many more Iraqis have died since March 2003 than one would expect without the war. Their conclusion, based on interviews of households and not a body count, is that about 600,000 died from violence, mostly gunfire. They also found a small increase in deaths from other causes like heart disease and cancer.
"Deaths are occurring in Iraq now at a rate more than three times that from before the invasion of March 2003," Dr. Gilbert Burnham, lead author of the study, said in a statement.
To better understand the figure, consider this: the same percentage of the much-larger American population would be 7.5 million dead, reported CBS national security correspondent David Martin.
The study by Burnham, of the Johns Hopkins Bloomberg School of Public Health, and others is to be published Thursday on the Web site of The Lancet, a medical journal.
At least one expert was skeptical of the new findings.
"They're almost certainly way too high," said Anthony Cordesman of the Center for Strategic & International Studies in Washington. He criticized the way the estimate was derived and noted that the results were released shortly before the Nov. 7 election.
"This is not analysis, this is politics," Cordesman said.
For Burnham's study, researchers gathered data from a sample of 1,849 Iraqi households with a total of 12,801 residents from late May to early July. That sample was used to extrapolate the total figure. The estimate deals with deaths up to July.
The survey participants attributed about 31 percent of violent deaths to coalition forces.
The work updates an earlier Johns Hopkins study — that one was released just before the November 2004 presidential election. At the time, the lead researcher, Les Roberts of Hopkins, said the timing was deliberate. Many of the same researchers were involved in the latest estimate.
Speaking of the new study, Burnham said the estimate was much higher than others because it was derived from a house-to-house survey rather than approaches that depend on body counts or media reports.
A private group called Iraqi Body Count, for example, says it has recorded about 44,000 to 49,000 civilian Iraqi deaths. But it notes that those totals are based on media reports, which it says probably overlook "many if not most civilian casualties."
Accurate death tolls have been difficult to obtain ever since the Iraq conflict began in March 2003. When top Iraqi political officials cite death numbers, they often refuse to say where the numbers came from.
The major funder of the new study was the Massachusetts Institute of Technology.
In other developments:The U.S. Army has plans that would keep the current level of troops in Iraq — about 15 brigades — through 2010, the top Army officer said. The Army chief of staff, Gen. Peter J. Schoomaker, cautioned that people not read too much into the planning, because it is easier to pull back forces than to get units prepared and deployed at the last minute. "This is not a prediction that things are going poorly or better," Schoomaker told reporters. "It's just that I have to have enough ammo in the magazine that I can continue to shoot as long as they want us to shoot."Violence around Iraq claimed at least six lives, including a parked car bomb that blew up next to a police patrol in southeastern Baghdad, killing two passers-by. The car bomb attack in the Ghadeer neighborhood also injured 10, including four policemen, Lt. Bilal Ali Majid said. A second car bomb attack a half hour later on a police patrol in the capital's eastern Mustansiriyah Square killed another two passers-by and wounded 16, including three policemen, Majid said. In southwestern Baghdad, a bomb exploded near an auto parts shop, killing the store owner and wounding four passers-by, police 1st Lt. Maithem Abdel Razzaq said. Elsewhere, gunmen shot and killed a policeman in the northern city of Kirkuk as he was heading to work, police Col. Anwar Hassan said.Sectarian violence, armed militias and death squads have created a situation in Iraq where revenge attacks go unchecked, the United Nations' top humanitarian official said, citing statistics that 100 people are being killed in the country every day. "Many of those are killed by gunshots or have been tortured to death," Jan Egeland said. "Revenge killing seems to be totally out of control."Saddam Hussein took his seat in the dock in his genocide trial, a day after the presiding judge threw him out of court in a raucous session during which witnesses testified that women were raped while in detention during a 1980s crackdown on the Kurds. Saddam and his six co-defendants sat quietly as chief judge Mohammed Oreibi al-Khalifa called a Kurdish witness to the stand. Tuesday was fourth time that al-Khalifa had ejected Saddam from the court since he became chief judge on Sept. 20.The U.S. command in Iraq confirmed the deaths of three U.S. Marines and two soldiers, killed in fighting earlier in the week. The Marines, assigned to 1st Brigade, 1st Armored Division, died Monday from enemy action in Iraq's western Anbar province, the military said in a statement. It did not provide further details. Also Monday, a U.S. soldier was killed when his patrol was attacked by insurgents in an eastern part of Baghdad, the military said. The second soldier, attached to the 25th Combat Aviation Brigade, died of wounds from an explosion during a vehicle patrol Sunday north of the city of Tikrit. No further details were available, and the soldiers' names were being withheld pending notification of family.A massive fire at an ammunition dump at a U.S. base in southern Baghdad was sparked by a mortar round fired by insurgents, which set off a series of explosions from detonating tank and artillery shells that shook buildings miles away, the U.S. military said Wednesday. The 82mm round was fired from a nearby residential area and hit Forward Operating Base Falcon around 10:40 p.m. Tuesday, spokesman Lt. Col. Jonathan Withington said. No injuries were reported. The Islamic Army in Iraq, a nationalist anti-occupation insurgent group, claimed responsibility Wednesday in a statement posted on the Internet. The U.S. military statement did not mention the claim or name any particular group as a suspect in the fire.