Calls are growing for Britain and the US to do more for the two million refugees who have fled Iraq since the invasion four years ago.
The UN refugee agency (UNHCR) says there has been an "abject denial" around the world of the humanitarian impact of invading Iraq.
The UN faces an enormous task in helping countries such as Jordan and Syria cope with the huge influx of Iraqi refugees, a spokesman said.
He said the international community had to step in to help address their food, health and education needs.
Syria says it is home to 1.2m Iraqi refugees, with up to 800,000 in Jordan.
Britain has taken just a few hundred refugees since 2003.
UNHCR spokesman Peter Kessler said: "There has been an abject denial of the impact, the humanitarian impact, of the war, the huge displacement within Iraq of up to 1.9 million people who are homeless because of the war, and those people who are homeless and never got back to the homes after Saddam Hussein was overthrown."
Many of the refugees need considerable support, and about a quarter of them are children who need education.
Many need food and healthcare, some need counselling because of the violence they have experienced or witnessed, while others need jobs.
"There's a need for governments to come in and address the health, the education, all the needs," Mr Kessler said.
"Food aid needs as well are becoming vital because the population is becoming further and further impoverished since they cannot work.
"So clearly in every area, there's a need to support what the main host governments are doing and then to gird ourselves for what could be, if the war is prolonged, an increasing movement further westwards."
On top of that, almost two million more people are displaced inside Iraq - people who have fled their homes to escape the violence.
Ekklesia's co-director Jonathan Bartley told BBC Radio 2's Jeremy Vine show; "Britain and the US were responsible for this mess. They have a duty to help to clean it up. This means being prepared to take more than a few hundred refugees.
"If Syria and Jordan, with much smaller populations than our own can take steps to provide for close to two million refugees, then we can certainly do our bit too. At the very least we should be undertaking to resource these countries. The cost would after all only be a fraction of the final bill for waging the war."