KHARTOUM, SUDAN -- Abuc Thuc Akwar, a girl of 13, was in a Dinka cattle camp in March when Arab raiders appeared on horseback. They surrounded the camp, firing machine guns in the air. Then, she said, they herded up several hundred of the Dinka tribe's cattle, kidnaped her and 24 other Dinka children and drove them all north.

They walked for 23 days out of the swamps of Dinka land, across the Bahr el Arab river and into the desert homeland of an Arabic-speaking tribe called the Misseirya. En route, she said her captors called her an Arabic word that means "black donkey." She said they raped her four times.

After crossing the Bahr el Arab, the raiders divided up their booty. Abuc said a Misseirya man named Ali took her home as his slave. She said she tended his sorghum fields in the daytime; at night, when he wanted her, she said she was forced to have sex with her owner.

As civil war grinds on in Africa's largest country, with more and more automatic weapons being put into the hands of tribal militias, western relief officials and Sudan government sources say there has been an eruption of slave-taking in central Sudan that is without precedent in this century.

Abuc, who managed to run away from her owner in June and find her way to Khartoum, is one of thousands of Sudanese women and children to fall victim to a tribal practice that appears to have been reborn amid the chaos of the four-year-old war.

Armed with AK47 automatic rifles and machine guns, unchecked by government authorities and motivated by centuries-old tribal rivalries, raiders reportedly are moving back and forth across the traditional border region that separates Sudan north from south, Moslem from Christian, Arab from African.

Southerners claim that Arab raiders, armed courtesy of the Khartoum government, have been given tacit approval to steal all the Dinka people and cattle they want. Northerners claim that southern rebels of the Sudanese People's Liberation Army (SPLA), armed courtesy of Ethiopia and the Soviet Union, are kidnaping Arab peasants and forcing them to work as porters.

"What makes this whole thing absolutely horrific is the introduction of automatic weapons," said Cole Dodge, country director in Sudan for the United Nations Children's Fund.

Dodge and other relief officials say that, besides triggering a dramatic increase in tribal slave-raiding, new levels of firepower on both sides of the war have led to tribal massacres, the theft of millions of head of cattle and the wholesale destruction of villages and cropland in central Sudan.

"There are too many arms and there is no law. The Gogrial district {a fertile Dinka region near the traditional north-south border} is being emptied of people and cattle. It has never been like this before," said Jacob Akol, a Dinka from Gogrial who is a spokesman in Kenya for World Vision, a California-based relief agency.

Many northern Moslems and southern Christians say that the escalation of firepower and the resultant increase in slave-raiding are developments that jeopardize the chance of any settlement of the civil war.

"What begins as defensive arming of militias quickly becomes offensive, as the guns are used to carry out a tribal agenda that has little to do with the civil war. It is a very dangerous situation," said Hassan el Turabi, leader of the fundamentalist National Islamic Front.

"It is now going to take an awfully long time for peace to be reestablished. The Dinkas are always going to want revenge," said Bona Malwal, a Dinka who is the editor in Khartoum of the English-language Sudan Times.

Maria Akwol, a Dinka woman, said that Misseirya raiders burst into her family's hut in the Gogrial district in April.

"They shot my husband immediately and they took my sons," she said. "They made me and my daughters walk for two months. They hit me with a gun in my ear and now I cannot hear."

Akwol said she and her daughters ran away from their owner at night. They arrived in Khartoum in early November and live now on the outskirts of town in a squatters' shack made of empty U.S. government food aid bags. She said she wants to avenge the destruction of her family.

"If I ever get the power, I will give the Arabs the same treatment they gave me," she said. "I would kill somebody's husband and take away their sons."

Tribal slavery is an ancient institution in Sudan, according to "The Southern Sudan," a book by Sudanese historian Mohamed Omer Beshir. He writes that slavery "was part of the structure of the societies of the south and the north, whether these were Moslem or pagan, Arab or Negro . . .

"Its origin and development lay in tribal warfare. Tribes took slaves irrespective of whether they were brown or black. When weaker tribes were conquered or raided by the stronger tribes, slaves were taken."

At the turn of the century, British rule in Sudan reduced but did not eliminate tribal slave-raiding. According to several Sudanese government officials, it continued at a low level while being tightly regulated by traditional law.

"Tribal conflicts and slavery have had their own mechanism of regulation," said Suleyman Baldo, a researcher at the University of Khartoum and co-author of a recent report on tribal massacres and the revival of slavery in Sudan.

"In the past, whenever Arab tribes raided the Dinka or when the Dinka raided the Arabs, there would be a peace conference among chiefs to settle the dispute," said Baldo. "They would count up the dead, the stolen cattle and the captives. Then they would determine who the aggressors were. The tribe that was the aggressor would have to pay compensation for the dead and for the cattle, and the captives would be released."

Until recently, Baldo said, the scale of tribal fighting had been limited by the available weapons -- swords, spears and clubs. If fighting did get out of hand, Baldo said government authorities were quick to intervene.

Since 1985, however, Baldo and a number of western relief officials say that tribal traditions have been crushed by the power of new weaponry. He charges, too, that the government in Khartoum has turned a blind eye to a level of violence "that is completely out of the context of traditional conflict.

"Official government support for the Arab militias has led to an atmosphere where Dinka cattle and Dinka people are considered free to loot," said Baldo. "Things have really gotten out of hand."

In an interview, Sadiq Mahdi, Sudan's prime minister, said that his government has armed Arab tribal militias. But he insisted that the militias operate under the strict control of the Sudanese military. While Mahdi acknowledged that there has been an increase in tribal slavery, he said that his government does not approve of it.

"This is a tribal malpractice," he said. "It exists in the tribal sector of Sudan and it is not accepted, not tolerated by the government. To portray it as government policy is most unjust."

The prime minister's denial notwithstanding, there is widespread agreement among relief officials, western diplomats and Sudanese politicians that Mahdi's policy of arming the Arab militias has helped destroy a fragile north-south tribal equilibrium and created conditions that encourage slave-taking.

Northern Sudanese, however, are quick to point out that SPLA rebel commanders have done much the same thing. Abdullah Suliman, director of the Islamic-African Relief Association in Khartoum, said his organization assists thousands of Arabs of the Rizeigat tribe whose homes and herds have been destroyed by Dinka raiders armed with machine guns.

Suliman said the Dinkas give the Rizeigats a choice of becoming porters or corpses.

While tribal slavery in Sudan is spreading with the worsening civil war, Abuc Thuc Akwar gives evidence of traditional values that work against slave-taking.

"The wife of the man who owned me was jealous," Abuc said. She said that one night when her owner had gone south for another raid in Dinka land, the man's wife came to her and told her to run away.

"She showed me where to walk on the railroad tracks toward {the town of} Muglad," Abuc said. "She told me to walk all night and not to worry because there were no wild animals that could eat me."