Updated

Hundreds of civilians are seeking refuge at a United Nations compound in the contested Sudanese town of Abyei following a spate of violence over the weekend that killed three people from north Sudan, officials said Monday.

More than 300 people, mostly men, have been inside the U.N. compound in Abyei since Saturday, when violence broke out between security officials and a youth mob later killed three northerners, the officials said.

Most of the people seeking shelter are Misseriya tribesmen from Sudan's north and Darfuris from Sudan's west. Other residents of Abyei are from a black African group and want the contested region to join Southern Sudan when it becomes the world's newest nation in July.

"They were subject to attacks and they are fearing for their lives. That's why they came" to the U.N. compound, said Kouider Zerrouk, the spokesman for the U.N. peacekeeping mission in Sudan. He said 303 people were in the compound.

Concerns over food security in Abyei began last month when nomadic Misseriya herders who need access to Abyei's fertile grazing land enforced a blockade of the trade routes from Khartoum, sending food prices higher in Abyei's markets.

Deng Arop Kuol, the top government official in Abyei, said Monday that Abyei police and forces from northern Sudan who are serving in a joint north-south army unit in Abyei traded gunfire on Saturday after a "misunderstanding." No forces from either side were wounded or killed, Kuol said.

After the exchange "a youth mob of angry civilians decided to fight with the traders and that is where the problem came," said Kuol. Three people — all from the north — were killed and seven or eight were wounded, he said.

The Abyei government has enforced a curfew since Saturday, he said. The situation has since calmed, he said.

Abyei also saw clashes last month in its disputed north-south border area. The region had been promised a self-determination vote in the 2005 peace deal that ended decades of war between north and south Sudan.

Southern Sudan voted last month to secede from the north and is set to become a new nation in July. The vote in Abyei did not occur due to tensions between Sudan's ruling parties in the north and south over voter eligibility.

Insecurity in Abyei also stopped thousands of southerners from migrating home from northern Sudan, resulting in bus convoys being stranded north of Abyei in neighboring Southern Kordofan state.

In a separate region of Southern Sudan, more than a hundred people were killed last week in Jonglei state in fighting between the southern army and a rebellious southern group opposed to the southern government. The fighting broke a cease-fire agreement between the army and the rebels brokered days before the south's Jan. 9-15 independence vote.

Nearly 99 percent of southerners voted for independence in their January referendum, but unity among the diverse population after their territory becomes the world's newest nation is less certain.

A heavily armed civilian population and unresolved grievances among southerners could lead to more violence before and after independence.