Two people were killed in clashes with police in eastern Congo on Monday after protesters in the town of Beni set fire to the mayor's office and several U.N. buildings in anger at a new round of violence by suspected Islamist rebels.

Rebels believed to belong to the Allied Democratic Forces (ADF) killed eight people in an overnight raid, police said, stoking residents' fury at the perceived inaction of both the government and a U.N. peacekeeping mission.

The police said protesters torched the mayor's office. A tweet by the police force showed flames shooting from the window and thick black smoke billowing above.

The protesters then marched to the offices of the U.N. peacekeeping mission in Congo (MONUSCO), said Teddy Kataliko, a civil society leader in Beni.

"Several offices at the MONUSCO headquarters were set on fire and looted," Kataliko said.  "Residents are demanding the withdrawal of MONUSCO from Beni because of the inaction of U.N. forces.”

Two people were killed by gunfire in the protests, Beni police commander Safari Kazingufu told Reuters.

The United Nations said one civilian and one policeman died, and that some of its offices were vandalized.

"We do understand the anger and frustration of the population but ask for understanding that attacking U.N. or local facilities... actually weakens the Congolese army's operations against the ADF," said Matthias Gillman, a U.N. spokesman.

The U.N. mission has not been participating in the army's offensive against the ADF launched late last month, he added, other than providing intelligence and medical assistance.