NAIROBI, Kenya - At least 2,000 people have died and 250,000 have fled their homes after violence in southern Sudan this year, worsening a humanitarian crisis in a region seeking its independence, officials from a medical aid group said yesterday.

Officials from Doctors Without Borders said this year's violence was the worst since the signing of a 2005 peace deal between southern Sudan and the north, an agreement that ended two decades of civil war.

The group's operations director in Sudan, Stephan Goetghebuer, said the 2009 killings were different from past violence in the south that was linked to land clashes and cattle rustling. This year, villages have been attacked, and raiders have targeted and killed women and children, he said.

The group said that 87 percent of the people it treated this year were victims of gunshot wounds but that the number killed in the violence was three times higher than the number of wounded.

"There are very few survivors," Goetghebuer said. "People are killed massively."

He said officials of Doctors Without Borders did not yet understand the underlying reasons for the attacks. The group has been working in Sudan for 30 years.

Sudan could face huge political upheaval next year that risks reigniting the country's civil war as the south prepares to vote for independence in early 2011.

A report on the humanitarian crisis in southern Sudan released yesterday by the group said that there were warning signs before some of this year's attacks but that neither the government of southern Sudan nor the U.N. mission in Sudan protected the communities.

Karla Bil, the group's medical coordinator, said at least 2,000 people had died in violence this year.

Shelagh Woods, deputy head of mission for Sudan, said the recent violence was exacerbating a dire humanitarian crisis, to which aid agencies based in southern Sudan have not adequately responded. She said the displaced were living in overcrowded camps without clean water, which led to the spread of deadly diseases such as cholera. Woods said that in one camp, the aid staff had treated 300 cholera cases.

She said that despite the large presence of aid agencies in Sudan, only a handful of them could respond to humanitarian emergencies quickly and effectively.

U.N. and Sudanese officials have expressed concern that the violence in the south could hamper preparations for national and presidential elections scheduled for April 2010. In January, Sudan will mark the fifth anniversary of the signing of the comprehensive peace agreement, which ended 21 years of civil war between northern Sudan and southern Sudan. An estimated two million people died from that conflict.