(CNN) -- The long-running conflict in the Democratic Republic of Congo has claimed hundreds of sexual violence victims in the past two months as women and girls continue to be prime targets of retaliation between rival militias along the country's porous borders, according to aid agencies.
At least 657 cases of sexual violence involving women and girls were documented in September and October during mass expulsions from Angola to Congo, according to UNICEF.
UNICEF, which compiled the case information over the past two months with help from aid agencies on both sides of the border, said women, girls and possibly men were sexually victimized as about 6,621 Congolese nationals were expelled from Angola.
"Many cases of VS [sexual violence] are reported, including torture," according to a UNICEF document obtained by CNN on Saturday.
A UNICEF spokesman in Kinshasa, DRC, said there have been 35 confirmed rapes so far as victims undergo medical evaluations in makeshift shelters set up by international aid organizations.
The U.N. plans to send a special mission, comprised of representatives from a variety of aid agencies, to the area next week to talk to community leaders, doctors and humanitarian organizations about the allegations, the spokesman said.
The Angolan deportations of more Congolese nationals were announced in August 2001, the report said. These mass-expulsions are making civilians more vulnerable to such attacks, the spokesman said.
Relations between the DRC and Angola -- once an ally -- have been strained. More than 10,200 Congolese nationals were deported from Angola in January and February of 2010. Several incidents of human rights abuse and sexual violence were reported associated with these expulsions as well, according to the United Nations.
Warring insurgent groups, such as the Ugandan-based Lords Resistance Army (LRA) and the Hutu-backed militia known as FDLR, operating in the eastern DRC are a main source for instability in the region, the agency said.
Rape has become a weapon of war in the Congolese conflict. The United Nations has named the Democratic Republic of Congo the "rape capital of the world," with 15,000 women raped in eastern Congo last year.
The attacks occurred in parts of the country where armed rebel groups moved into areas considered to be pro-government but lacking in army or police protection, according to the U.N.
Often dubbed the Great African war, analysts say the conflict in the DRC -- considered Africa's oldest and deadliest war -- has cost the lives of nearly five million people. Nine African nations were involved in the conflict that spilled over from the 1996 Rwandan genocide.
CNN's Umaro Djau contributed to this report.