M23 denies Human Rights Watch findings linking it to massacres in eastern Congo, as rights groups cite mass killings and the U.S. urges U.N. action.

Democratic Republic of Congo’s army accused Rwanda-backed M23 rebels of attacking its positions in the east of the country and threatening peace talks overseen by the US and Qatari governments.

The Rwanda-backed rebel group M23 has denied involvement in recent massacres in eastern Congo. A report by Human Rights Watch, released Wednesday, accused M23 of killing over 140 civilians.