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, was said to have been killed in a predawn drone strike near the North Kivu province’s mining town of Rubaya.

The 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.

Rubaya residents told the AP that the drone strike targeted a spot that has in recent weeks served as an enclave for the M23.

The decades-long 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. The conflict has created one of the world’s largest humanitarian crises, with more than 7 million people displaced.

It wasn't immediately clear who carried out the drone strike, viewed by many in Congo as a setback to peace efforts that partners hoped would bring permanent peace and prevent a regional conflict.

The drone strike came weeks after both Congo and M23 rebels agreed to a ceasefire and methods of monitoring it with help from the U.N.mission in Congo. Both parties traded accusations of violating the terms of the truce.

U.S. President Donald Trump and Qatar have brokered peace efforts, but clashes have continued in recent weeks.