The study by Medact, the British affiliate of the International Physicians for the Prevention of Nuclear War who won the Nobel Peace Prize in 1985, examines the likely impact of a war on Iraq from a public health perspective.

Estimates of the total possible deaths on all sides during the conflict and the following three months range from 48,000 to more than 260,000. A possible civil war in Iraq could add another 20,000 deaths, the report said. Additional deaths from post-war adverse health effects could reach 200,000.

The report warns that if nuclear weapons are used, up to four million people could die.

The report marks the first public assessment of the consequences of a war on Iraq, Jane Salvage, international health consultant and author of the report, said at its Nov. 12 release.

"How can we debate the pros and cons of an attack on Iraq if we don’t know what the consequences will be?" she asked.

The report was written after extensive consultation with doctors, nurses, Iraqi health specialists and specialists on the effects of war on health from the United States and Britain, Ms. Salvage said. Former chief of the Australian military, Gen. Peter Gration, called the report militarily sound, Ms. Salvage added.

The likely course of an attack on Iraq is outlined in the report as a heavy aerial attack aimed at destroying military installations and infrastructure. The report envisages destruction of roads, telecommunication centers and electrical supplies.

This would be followed by an invasion from the South to target the oilfields "but there may be an attempt by Saddam to sabotage them," she said. There would be another attempt to invade from the North and then target Baghdad and other cities. The invasions would destroy numerous civilian facilities, Ms. Salvage said.

The destruction of electrical supply can have a direct and devastating consequence on health, said Mike Rowson, director of Medact. Lack of electricity has been a crucial factor in child mortality and in the health profile of a country, he said.

The Medact report said there are several effective alternatives to war. These could include sanctions aimed at the country’s elite, giving enough time to UN inspectors and making sure they work objectively, creating a visible system to contain flow of weapons-related goods into Iraq, developing political processes to disengage the components of the Iraqi regime from one another and creating a reconstruction plan to encourage a post-Saddam rule of law.

"Assumptions that Saddam Hussein would roll over easily are misplaced," said Ms. Salvage. "The U.S., aim is regime change, and Saddam’s aim is regime preservation," she said. "And we have all seen how wily he can be at that game."

In targeting Saddam Hussein, Western powers are disregarding the consequences for the Iraqi people, Ms. Salvage said. "The Iraqi people have been kicked once by the Gulf War, a second time by sanctions, and are they going to be kicked a third time?" she said. "If a war scenario meant a minimum of 50,000 British or American deaths, would anyone be talking war? Is there something less about an Iraqi life?"

The report warns the aftermath of a conventional war could include famine and epidemics, millions of refugees and displaced people, and economic collapse in Iraq. Destabilization and possible regime change in neighboring countries, and more terrorist attacks on a worldwide scale are possible, the report said.

With arms spending, occupation costs, relief and reconstruction, the war’s cost could exceed $150 billion to $200 billion, the report noted.

The casualty estimates are drawn from a study of the Gulf War and from conflicts in Somalia and the Balkans, and from information on the current state of health in Iraq.