GOMA, Congo — Rebels backed by Rwanda captured more towns in eastern Congo on Wednesday as they moved beyond the key city of Goma in an apparent attempt to expand their control in the conflict-battered region.

The rebels advanced toward the center of South Kivu province after taking several towns, including Kalungu, Kanyezire and Mukwinja, according to a local civil society leader and an aid worker in the area. They spoke on condition of anonymity because they were not authorized to talk to the media.

U.N. spokesman Stephane Dujarric said the developments were concerning, and that the United Nations was taking measures to protect civilians and U.N. staff. The advance also raised fears of a prolonged occupation by the rebels, who have said they plan to set up a new administration in Goma, a city of 2 million people.

“Left unchecked, the fighting could spread ... recalling the horrors of the late 1990s and early 2000s, when millions died,” the Crisis Group said, citing the last, multi-country war there.

— The Associated Press