GOMA, Congo — The U.N. Security Council agreed Thursday to send 3,100 more peacekeeping troops to Congo, while rebels said they remained committed to a pullback from the front lines despite an army attack.

There are currently 17,000 peacekeepers in the vast Central African nation — the world's largest U.N. peacekeeping mission — but they have been unable to stop the fighting.

On Thursday, rebels said they had fended off an attack from the army, pro-government Mai Mai militias and Rwandan Hutu rebels.

Rebel spokesman Bertrand Bisimwa said their troops were attacked in Katoro, a small village near Kiwanja, about 45 miles (70 kilometers) north of Goma. Rebels fended off the attack after two hours "and the situation is now calm," Bisimwa said.

He said rebels were still committed to keeping their troops pulled back from front lines further north, but warned: if the U.N. peacekeeping force "is not able to keep quiet in this area ... we'll go and attack these groups who are trying to take control of that area."

The reported attack came a day after the U.N. confirmed that hundreds of rebel forces had pulled back from three front lines in eastern Congo. U.N. peacekeeping spokesman Col. Jean-Paul Dietrich had called the move "a positive step."

The U.N. was hoping the rebels' deliberate retreat would be one step toward brokering peace in Congo, where at least 250,000 people have been displaced by the recent violence.

In New York, U.N. Secretary-General Ban Ki-moon welcomed the pullback by Nkunda's forces and urged the quick opening of humanitarian aid corridors.

"(Ban) calls on the parties to observe the cessation of hostilities and to guarantee safe passage of humanitarian assistance" as efforts continue to find a political solution to the crisis, his spokeswoman Marie Okabe said.

Years of sporadic violence in eastern Congo intensified in August, when fighting heated up between the army and fighters loyal to rebel leader Laurent Nkunda.

Nkunda says he is protecting Tutsis from Hutus who fled to Congo after Rwanda's 1994 genocide. But critics say he is more interested in power and accuse his forces of committing multiple human rights abuses.

An Associated Press reporter verified the withdrawal on one of the fronts just south of Kanyabayonga at Rwindi, the northern headquarters of Virunga National Park, home to some of the world's last remaining mountain gorillas.

On Wednesday, Rwindi's main road was empty, with rebels visible only a few dozen miles to the south at a park station checkpoint that had been abandoned by rangers. Herds of elephants roamed fields of pristine green savannah grass in the area. Baboons scurried across empty roads.

Associated Press Writer John Heilprin at the United Nations contributed to this report.