Hundreds of millions of children living in urban areas lack clean water, improved sanitation, and other basic needs, according to “The State of the World’s Children 2012,” a new report from UNICEF.

The number of poverty-stricken urban children is growing rapidly because of increased migration and urbanization, the United Nations children’s agency says.

“When we think of poverty, the image that traditionally comes to mind is that of a child in a rural village,” says UNICEF Executive Director Anthony Lake.

However, in Africa and Asia, many poor families – and even children on their own – are moving from rural areas into cities to look for work.

Living in makeshift slum dwellings, they often lack clean water, improved sanitation, and schooling.

Among the worst off are tens of millions of children who live on urban streets. They are often victims of violence, trafficking, and exploitation.

UNICEF says the true plight of urban children is often hidden by statistics that group together rich and poor city dwellers.

Download the full UNICEF “The State of the World’s Children 2012” report here(PDF).