Action German Helps (ADH) - grouping nine aid organizations based in Germany - said it believed the war could lead to several million refugees and victims.
United Nations relief organizations estimate 600,000 refugees will flee to neighbouring countries Syria, Jordan, Kuwait and Iran. ADH said as many as two million people could also be forced to flee cities to mountainous regions of Iraq.
It said around 10 million people would need to be provided with food, water and medicines.
Aid groups have already made plans for an expected rush of refugees and the collapse of Iraq's infrastructure.
World Vision has sent a planeload of relief goods to Jordan, while the United Nations Children's Fund UNICEF has two trucks with first aid kits and water purification tablets for Baghdad awaiting clearance at the Jordan border.
Emergency supplies such as health kits and high protein foods for malnourished children have been stockpiled in neighbouring countries.
UNICEF has 160 workers in Iraq including Baghdad, Basra and Kurdish regions of northern Iraq, while CARE aid organization has 60 helpers assisting hospitals and health centres.
Among other aid organizations involved in humanitarian work, Germany's Diakonie Katastrophenhilfe has established 18 aid centres in mosques, schools and churches in Baghdad, Basra, Mosul and Kirkuk, and set up refugee camps in Syria and Jordan.
dpa bw AP-NY-03-20-03 1101EST
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