Nearly two million Iraqis have fled their homes for other parts of Iraq since the US invasion, creating a "unprecedented human tragedy," the country's Red Crescent said in a report.
The figure covers only those internally displaced and does not include the UN-estimated two million others who have also fled but left their homeland completely, to go to Syria, Jordan, other neighbouring countries and even to Europe.
As at August 31 this year, 1,930,946 people had left their homes to seek safety elsewhere within Iraq's borders since the March 2003 invasion, creating a record in the annals of Iraq's human upheaval, the humanitarian society said.
Most were women and children - poor, sick, suffering from malnutrition and with little access to the country's health infrastructure or basic services. "Heads of families have very often fled or joined an armed group... Rape, armed gangs, theft, drug addiction" were commonplace among internally displaced people, the Red Crescent said.
"The horror of daily slaughter and attacks has a serious impact on the psychological health of the women and children. The overall picture is that of a human tragedy unprecedented in Iraq's history."
According to the Red Crescent, the number of displaced people increased by some 71 percent in August compared to July, with most of the increase in Baghdad. The capital now had nearly one million displaced people for an estimated total population of four to five million, it said.
The report offered no explanation for the sudden jump in Baghdad residents leaving their homes, but it coincided with the sixth month of a vast US military offensive or "surge" to try to improve security there. US claims of success in the battle against armed groups could have spurred civilians to flee during a period of relative calm.
The humanitarian group said the attack on the Shiite shrine in Samarra in February 2006 spurred the exodus of thousands of Iraqis when it unleashed widespread sectarian violence.
"Thousands of Shiites fled Sunni zones, and vice-versa. Many Christians also left Sunni districts to go to Kurdistan" in northern Iraq, where recent Turkish and Iranian bombardments of frontier regions have also prompted thousands to flee.
The Iraqi Red Crescent is one of the rare humanitarian organisations still active in the war-ravaged nation. Separately, the UN refugee agency has said that 1.4 million Iraqis have now sought refuge in Syria, with between 500,000 and 750,000 in neighbouring Jordan.