KINSHASA, Congo (AP) — A spokesperson for the Rwanda-backed M23 rebels fighting in eastern Congo has been killed in a drone strike, a local U.N. official and a rights group said Tuesday, escalating tensions over the region's conflict after peace negotiations stalled.

Willy Ngoma, a senior officer who was deeply involved in M23's operations in eastern Congo, was said to have been killed in a predawn drone strike near the North Kivu province’s mining town of Rubaya.

The local U.N. official and a coordinator with the rights group working in the area spoke to The Associated Press on the condition of anonymity for fear of their lives.

Residents told the AP that the drone strike targeted an area that has in recent weeks served as an enclave for the M23.

The decadeslong conflict escalated in January last year after the rebels made an unprecedented advance into the key cities of Goma and Bukavu, further expanding their control of several cities and towns in the hard-hit region.

It wasn't immediately clear who carried out the drone strike. Despite peace efforts by U.S. President Donald Trump and Qatar, clashes have continued in recent weeks between the rebels and the Congolese forces, joined by the local Wazalendo militia group.

M23 and Congolese authorities didn't immediately respond to an inquiry. Both parties have accused each other of violating terms of a ceasefire reached with the help of foreign and regional partners.