A Darfur refugee cradles her child at a camp in Chad
Africa's largest country is emerging from a 21-year civil war between the north and south. A separate conflict raging in the arid western Darfur region has caused massive displacement. Another insurgency is brewing in the east.
More than 1.75 million Darfuri children live in and around camps.
Girls risk rape when they leave camps and villages to gather firewood.
Teenage boys are recruited to fight in armed groups.
One agency says a third of children in camps are working and 15 percent have some type of physical or emotional disability due to atrocities they have experienced.
Nearly 18 percent of children in east Sudan have acute malnutrition - WFP.
"People are living in a virtual state of lockdown, unable to fully pursue independent lives, trapping families and children in a state of bare survival and little hope."
No Child Soldiers poster from the French Organization, Demobilisons les Enfants Soldats
"The most dangerous places are those conflict zones where children are actively recruited into the fighting forces, and the current worst offender...is Uganda's Lord's Resistance Army," said Gareth Evans, head of the International Crisis Group think tank.
"Its recruiting, indoctrination and battle tactics have left countless children either dead, or dreadfully physically or mentally scarred."
During its brutal, two-decade insurgency, the cult-like rebel group has kidnapped up to 25,000 children to serve as soldiers and sex slaves. Each evening about the same number of child "night commuters" trudge into towns to avoid abduction.
Amnesty International: Child Soldiers
"What makes it even more dangerous is that no one is hearing about it... The long-standing and invisible nature of the situation has led to an entire generation of children growing up in camps," said Krista Threefoot of aid group Catholic Relief Services.
Military recruitment is also a major risk for children in Congo, as highlighted by former BBC war correspondent Martin Bell. "Despite partial demobilisation, (Congo) is believed to have more child soldiers than any other country in the world," he said.
He also pointed out that, here and in his other choices of Darfur and Iraq, poor security means large proportions of the population are beyond the reach of the aid agencies.
Congo's first free elections in 40 years, set for the end of July, are meant to draw a line under its 1998-2003 war that killed millions, but conflict still simmers in the lawless east, where disease, hunger and violence kill about 1,200 a day.
"Women and children are regularly targeted by illegal and armed militias and other predators, who perpetrate unacceptable acts of violence and rape against them," said U.N. aid chief Jan Egeland, who also selected northern Uganda and Afghanistan.
This video brings together Ben Okafor with other African artists: Alpha Blondy, Kidjo Angelica, Mama Keita, Lokua Kanza, Bibie, Monique Séka, Charlotte M"Bango, Aïcha Koné and Madéka. Their performance speaks to taking action to fight against the exploitation of the children soldiers.
Some 1.8 million children have been affected by a three-year conflict in Darfur, according to the U.N. Children's Fund (UNICEF), where they risk being recruited to fight and are especially vulnerable to disease and malnutrition.
"It is a traumatised population and you can see it in the children's faces," said Hollywood actress and UNICEF goodwill ambassador Mia Farrow, who last month visited camps for some of the 2.5 million displaced by Darfur's war.
"Everyone has lost family, seen villages burn, seen relatives raped, been raped."
U.N. High Commissioner for Refugees Antonio Guterres - who selected Congo, Uganda and the Sudan/Chad border, where some 200,000 refugees from Darfur eke out an existence - pointed to the physical and psychological consequences of living in crowded, underfunded camps "which are not conducive for a healthy child development".
In southern Sudan, children also suffer the effects of low-level violence, poverty and a lack of basic services. The region is struggling to recover from a 21-year civil war with the north that killed 2 million people, as 600,000 refugees forced to flee the country trickle home.
AlertNet, a humanitarian news website run by Reuters Foundation, asked 112 aid experts and journalists to highlight the world's most dangerous places for children.
After Sudan, they chose northern Uganda, Democratic Republic of Congo, Iraq, Somalia, India, the Palestinian territories, Afghanistan, Chechnya and Myanmar - with the top three clearly ahead.
More than 2 million children worldwide have died as a direct result of armed conflict in the past decade, and about 20 million have been forced to flee their homes, according to UNICEF. More than a million have been orphaned or separated from their families.
Every day thousands of children pick up a gun and go to war. Others trudge miles in the searing heat to look for water and food. Some have to do both.
This factfile highlights the most dangerous places in the world to be a child as judged by a Reuters AlertNet poll of humanitarian workers and journalists.
The three worst places are all in Africa where war and drought has brought death, disease and displacement to millions.
But not all the regions named are ravaged by conflict. India is ranked sixth - reasons given include poverty, malnutrition and child labor.
Sudan, Uganda and Congo are the world's three most dangerous places for children due to wars that have brought death, disease and displacement to millions, a Reuters AlertNet poll showed on Tuesday.
Around half of respondents picked Sudan as one of their three choices, with many singling out the troubled western region of Darfur. Some 1.8 million children have been affected by a three-year conflict in Darfur, according to the U.N. Children's Fund (UNICEF), where they risk being recruited to fight and are especially vulnerable to disease and malnutrition.