Tue Apr 1, 2:07 PM ET

The number of internally displaced Iraqis rose to more than 2.77 million people by the end of March, some five years after the US-led invasion to topple Saddam Hussein, the UN refugee agency said Tuesday.

More than half of the displaced were uprooted after the Al-Askari shrine bombing in Samara in February 2006 which sparked a wave of ethnic violence across the country, UNHCR spokeswoman Jennifer Pagonis told journalists.

The new report was produced by UN High Commissioner for Refugees, the International Organisation for Migration, and other UN agencies and NGOs.

Displacement was now continuing at a much lower rate, at least partly because communities were now much more homogenous, as many minorities targeted for persecution had sought refuge among their own kind.

Although there had been a small trickle of people returning to their original homes, only a few families have returned to areas under the control of another sect, it noted.

"No members of minority groups (Christians, Sabaean-Mandaeans and Yazidis) have been reported to be among the returnees," the report said.

The IDPs' lot remains miserable with more than a million people in need of adequate shelter and food and more than 300,000 people without access to clean water.

Two million Iraqis have also fled to neighbouring Jordan and Syria, where social and health services are struggling with the influx.

The UNHCR in January launched an appeal for 261 million dollars (167 million euros) to help all displaced Iraqis, but said Tuesday it had only received a third of this amount.