A British-based medical group warned Tuesday that nearly half a million people could die if there is a conventional war in Iraq. Such a conflict could also have long term environmental and humanitarian implications, the group said.

"The threatened war on Iraq could have disastrous short, medium and long-term consequences not only for the Iraqi population and its neighbours, but also further afield," said a report released by Medact, a group affiliated with the Nobel Prize-winning International Physicians for the Prevention of Nuclear War. In Canada, the report was unveiled by the affiliate group Physicians for Global Survival.

According to the report, entitled Collateral Damage: The Cost of War in Iraq, a war could result not only in direct casualties, but in a devastating and deadly aftermath.

Medact's projections are based on UN casualty figures from the 1991 Gulf War, though the group says given the U.S. aim of ousting Iraqi President Saddam Hussein and the availability of more modern weaponry, the impact of a new war would be far greater than a decade ago.

"A fresh conflict is likely to be wider-ranging and use a new arsenal of weapons, and its impact is likely to be more profound," said the report.

"We tried to draw up a credible war scenario," Jane Salvage, author of the report, told a London news conference Tuesday.

Medact estimates that between 48,000 and 260,000 people on all sides could die during a conventional war and in the three months afterward.

But those numbers are just the tip of the iceberg.

"A war against Iraq carries formidable risks: it could result in substantial civilian casualties and lead to the use of weapons of mass destruction. If the regime does not collapse quickly, scenarios become increasingly risky and less easy to predict or control," says the report.

"Any assumption that (Saddam) would roll over easy would be misplaced," Salvage said.

According to the scenarios examined by the group, a war would result in major damage to Iraq's infrastructure, including the destruction of roads, railways. homes, hospitals and sewage plants. That would create conditions in which disease would flourish, Medact says. The groups estimates the death toll from adverse health effects, including disability, infectious diseases and malnutrition, could reach 200,000.

Though Iraq is not believed to possess nuclear weapons, the U.S. has warned it will respond strongly to the use of any weapons of mass destruction.

"An Iraqi (chemical or biological) attack on Israel or elsewhere could provoke immediate nuclear retaliation from Israel, the U.S. and/or UK while the UK and U.S. have not ruled out the nuclear first-strike option," said the report.

In the event of a nuclear attack, the death toll could balloon to four million, Medact said.

As well, the group says Saddam could retaliate by setting fire to oil wells or by attacking Kuwaiti or Saudi oil fields or civilian centers in other Gulf states.

The U.S. is threatening war if Iraq refuses to comply with Friday's unanimous UN resolution ordering disarmament and granting weapons inspectors complete access.

Tuesday, Iraqi parliament voted unanimously to reject the resolution, leaving the final decision to Hussein, who has until Friday to respond.

Given the consequences Medact says there are "many options on the spectrum between 'doing nothing' and going to war, even if Iraq refuses to comply."

"The need to ensure that Iraq is disarmed of its weapons does not warrant a war," said Gill Reeve, Medact's assistant director.