UNICEF is warning that tens of thousands of people are at risk because they cannot freely move within their communities, cut off from clean water and food supplies by snipers or by roads laced with improvised explosive devices.

The Sadr City area of the capital has seen the worst clashes between government forces and Shia militia.

The agency said that over 150,000 people there are having difficulty accessing clean water, food and other essential services.

The Iraqi government says almost 1,000 people have died in recent fighting.

Most of those have been civilians, and aid agencies say around 60 percent of them are women and children.

For seven weeks now Iraqi forces, backed up by US troops, have been trying to disarm Shia militiamen, but they have faced stiff resistance.

In addition, hospitals are reporting shortages of medical supplies, while other health facilities open and close depending on the ability of staff to turn up for work, and are often in locations too dangerous for patients to use.