UN warns of five million Iraqi refugees

He returned to his home in al-Jihad, but when he arrived his neighbours said that the Mahdi Army Shia militia had left a message for him. It said that if he ever re-occupied the house, they would kill him.

Omar moved to the supposedly safer Sunni district of al-Khadra, but now he faces another problem. Al-Qa'ida insurgents are demanding that he join them on nightly patrols.

First they asked him politely to meet their emir or local leader. Later, when he failed to do so, they became more menacing.

They said: "Either you come with us or you will have to leave here. We suspect that you are not a Sunni, because a real Sunni would not hesitate to join the jihad."

Across Iraq, millions of people are looking for safer places to live, and not finding them. The United Nations High Commission for Refugees (UNHCR) reported last week that 4.2 million Iraqis have been forced out of their homes.

There are also ominous signs that the four-month-old US security plan for Baghdad is failing to reduce the level of violence despite an extra 17,000 US troops in the capital.

"The situation in Iraq continues to worsen," the UNHCR announced, "with more than two million Iraqis now believed to be displaced inside the country and another 2.2 million sheltering in neighbouring states."

The Iraqi refugee crisis is now surpassing in numbers anything ever seen in the Middle East, including the expulsion or flight of the Palestinians in 1948.

Since the sectarian pogroms that followed the destruction of the Shia shrine in Samarra in February 2006, an estimated 850,000 people have been displaced within Iraq, including 15,000 Palestinians who have nowhere to go.