Disease and a lack of clean water are killing 20 children every day in squalid camps of eastern Congo, victims of ethnic-driven violence that has created the world's worst humanitarian crisis, U.N. (search) officials said Friday.

Those deaths may be an indicator of a much larger tragedy, according to U.N. and government security officials who on Friday toured three sprawling camps in remote Ituri province, where about 75,000 people have fled to escape being killed by militia prowling the surrounding hills.

"The people in the camps we're able to reach," said Ross Mountain, humanitarian coordinator for the U.N. mission in the Congo (search). "The tragedy is what we're not seeing."

Thousands of children and adults gathered behind a cordon of razor wire in the Che, Gina and Kafe camps to greet the white U.N. helicopter carrying the visitors, before parting to reveal a sea of ratty green tents amid a haze of cooking fires.

For years, Lendu militias have targeted rival Hema tribespeople with murderous raids and macabre massacres. Hema militia respond by killing Lendu civilians.

Recently, raids that were sporadic have become an almost daily event and spread to every corner of the province.

Since December, Lendu attacks have caused nearly 100,000 people to flee into the sweeping hills of Djugu (search) territory, U.N. officials say.

Hundreds of U.N. peacekeepers and government troops are now deployed at the camps, scrambling to ward off attackers and keep disease and hunger at bay.

Nearly 20 children die each day among 25,000 people in Gina camp, mostly from measles and diarrhea, said Rachel Scott, spokeswoman for the U.N. Office for the Coordination of Humanitarian Affairs.

Overcrowding, lack of water and sanitation, plus the sudden crush of arriving displaced people contributed to the rapid spread of sickness and disease, she said.

About four kids are dying daily in Che camp despite efforts by several humanitarian organizations offering round-the-clock assistance to the camp's 24,000 inhabitants.

Children make up nearly 80 percent of the camp populations, according to the United Nations.

Fighting between the Hema and Lendu militias has left more than 50,000 dead in Ituri since 1999, according to the United Nations and aid groups.

The Congo killing and dislocation have overtaken the attacks in Sudan's Darfur region as the worst humanitarian crisis in the world, the U.N.'s humanitarian chief Jan Egeland, said March 16.

The Ituri conflict is a bloody sideshow to Congo's larger five-year war, which ended in 2002. It claimed nearly 4 million lives, mostly through starvation and disease, aid groups say.

The same militias are believed to have killed nine U.N. peacekeepers last month near Che, 37 miles north of Bunia (search), the provincial capital.

Peacekeepers responded by killing nearly 60 militia who they say fired on one of their patrols.

Harrowing stories of camp residents describe how they narrowly escaped from Lendu raids, only to reach a relative safety where they fear their children will die of simple infections.

"This is a country that has almost every disease known to man, and they all hit the kids first," said Mountain.

In the crook of a lush green valley where Che camp has grown, Longa Losa told how he fled an attack on his nearby village with eight children, but only after watching Lendu militia shoot dead three of his sons.

"People are here helping us," said Losa, 65, who wore a tattered fedora and flip-flops. "But it's still not enough. We eat every two days."

Ali Mohammed, 60, escaped an early-morning raid in his village eight kilometers (five miles) away, arriving at the camp in the nightgown that he still wears.

He said the militia hacked his two children to death with machetes, then shot and killed his mother.

"They came at dawn with guns, spears and machetes," said Mohammed, a farmer. "They screamed 'We have come, and now you are going to heaven.' Then they started killing us."