GOMA, Democratic Republic of Congo (Reuters) - Twelve Congolese soldiers were killed alongside seven U.N peacekeepers in clashes with militias on Wednesday in Democratic Republic of Congo’s Ebola-hit east, government spokesman Lambert Mende said.

The casualties, incurred during a joint operation against the Ugandan Islamist group Allied Democratic Forces (ADF), make this week one of the deadliest for troops in Congo’s volatile eastern borderlands since a rebel attack in early 2018.

Earlier on Friday, a U.N. source told Reuters up to 50 Congolese soldiers were wounded in the joint operation.

Speaking to Reuters by phone, Mende confirmed that 12 Congolese soldiers had been killed and many wounded in the fighting, without giving an exact number.

The deaths of the U.N peacekeepers, six from Malawi and one from Tanzania, were reported by the United Nations on Thursday.

Eastern Congo has been plagued by banditry and armed insurrections for more than two decades since the fall of military ruler Mobutu Sese Seko, but the past year has seen a surge in violence around North Kivu region.

The insecurity is hampering international efforts to contain an Ebola epidemic, the worst in Congo’s history, that has infected over 300 people and killed two-thirds of them since July.