The hulking sacks of food aid have long since arrived. But gathering the firewood needed to cook the grain presents a more vexing problem for the African women of Darfur.

They work with trepidation. Armed Arab militiamen, known as the Janjaweed, roam the scrubby green fields of western Sudan where the women collect bundles of wood. The militia continues to rape and attack villagers in this region, aid workers say.

On a cool morning recently, women in a line moved quickly across a wide field, wooden axes balanced on their heads.

"I run just to collect what I can. But it's still not enough for my family," said Fatima Mohamed, 24, nine months pregnant. Wearing a billowing purple shawl, she hunched over a pile of branches and picked out the thorns. "I thought things were getting better here. Food is okay now. And water is okay. But security is so bad. It's our greatest concern. My heart is always fearing."

Six months ago, the United Nations called the situation in Darfur the worst humanitarian crisis in the world. Aid workers were forced to wait months for visas to enter the area, and feeding centers swelled with malnourished children.

Now, after intense international pressure on the government, the larger camps are open to relief. U.N. officials say food aid is reaching the area and health conditions are slowly improving.

Although hepatitis E, a sometimes fatal disease, is on the rise in camps, epidemics have been staved off, largely because of a light rainy season and functioning latrine systems. The high number of deaths that relief agencies had feared have so far been averted.

But aid organizations said any lasting triumphs depend on peace. Without security, a generation in Darfur may remain trapped in these congested camps, afraid to return to their homes. More than 5,000 people arrived at camps just this week, fleeing reports of fighting in southern Darfur, aid workers said, and many fear that a health and food crisis could develop again.

"It's a mistake to just feed people and forget the security situation," John English, program manager for Save the Children, said in Nyala, the capital of South Darfur province. "The violence is everywhere, and we receive reports of attacks regularly. Women are raped. People feel pressured to go home to villages, but they don't feel safe. They are hemmed into these camps and trapped."

The fighting in Darfur broke out last year when two African rebel groups attacked police stations and military outposts, charging that their tribes faced political and economic discrimination. The government responded by arming and supporting the Janjaweed, an Arabic word that is often translated as "devils on horseback," to crush the rebellion, humanitarian groups say. Tens of thousands of people have been killed in the violence, and more than 1.5 million have been uprooted from their homes. The government has admitted backing some of the militiamen but contends that most are simply criminals beyond its control.

The government allowed the African Union to dispatch about 135 military observers and a 300-member protection force to Darfur to monitor a cease-fire. Facing international pressure, and with the threat of U.N. sanctions looming, the government agreed to allow 3,500 additional monitors and protection forces into Darfur. African Union troops would be allowed to work with and supervise Sudanese police but would not be allowed to use force against combatants to protect civilians.

International human rights organizations praised the government for accepting the forces but stressed that people will return to their villages only if the African Union is allowed to stop attacks.

"The primary objective of any international force must be to establish security for the safe and sustainable return of the displaced and refugees back to their home villages, in effect reversing the ethnic cleansing that has occurred," said John Prendergast, an Africa expert at the International Crisis Group, based in Washington. "If the force does anything other than this, it will condemn the displaced to living in camps indefinitely . . . and will do little to protect civilians, particularly women, who continue to be attacked on a regular basis in Darfur."

At Kalma camp, a site 15 miles northeast of Nyala where about 70,000 people live, village elders said officials are pressuring them to return home even though the countryside remained unsafe. The elders and aid workers said the government was trying to make it appear as if the crisis had ended. Sudanese officials deny that, saying they just want people to return to their villages and resume planting.

On a recent night, police cars sped through the grounds, terrifying residents who thought they were going to be forced to leave, aid workers said. On another night, shots rang out from a police station operated by the government in the camp, they said. Many people accuse some of the officers of being former Janjaweed.

Over the past two weeks, the governor of Nyala made six radio announcements urging people to return to their villages. The Sudanese Women's Union, a government-backed organization based in Khartoum, the capital, visited the camps and also told people to leave the camp. Days later, a government official told refugees that trucks would arrive to transport more than 100 people to their villages. Sugar and grain have been offered as incentives to return.

But few of the refugees want to go. Some who tried months ago have returned, reporting that they were attacked a second time.

Abdullah Mohamed Adam, 55, arrived at the camp after a Janjaweed attack in May. "I had 13 cattle, 67 sheep, eight donkeys and two cats," he said. "Yes, I was a rich man. Everything was taken."

After living in a particularly congested area in Kalma's tight labyrinth of huts for two months, he agreed to return home. He surrendered his World Food Program ration card and spent most of his tiny savings on transporting his family -- two wives and nine children -- back to the village of Ganjou, 55 miles north of the camp.

When the family arrived, all that was left of their home was a pile of rubble. Adam spent the rest of his savings rebuilding and began planting groundnuts and tomatoes. "I was renewing everything," he said.

But in July, the Janjaweed came again.

"We ran with our clothes on and nothing else," he said. "We didn't even have money for any transportation. We had to walk back to Kalma."

Adam said he would not consider returning again. "Where else can we go?" he said, crying. "They didn't protect us. They deceived us."

Hadja Sullima Bakdem, 19, said she was attacked last month near the camp while collecting firewood. She said she was pushed to the ground by a man she described as a Janjaweed but escaped.

Now she does not leave the camp and gathers twigs from the nearly empty branches of a tree.

"This is the climate of fear for us today," she said, leaning against the tree. "Security is not okay here. I feel scared sometimes."

Just steps away, a group of women journeyed out together to collect the stacks of firewood, saying they knew of the attack on Hadja but wanted to try anyway. They spent over an hour hacking branches under a relentless sun. They formed a long column and quickly walked off to the camp, heads pilled high with wood. All the while, they said, they glanced around them and into the wide-open fields, hoping they were safe.

A schoolboy displays his drawing of a Janjaweed attacker. Teachers say that Sudanese children have been traumatized by the militia attacks in Darfur.Women traveling in groups for safety carry firewood back to Kalma camp.