More than 400 civilians have died in eastern Congo’s South Kivu province since the escalation of an offensive by the Rwanda-backed M23 armed group, regional officials reported, noting the presence of Rwandan special forces in the strategic city of Uvira.

A spokesperson for the South Kivu government said late Wednesday that "more than 413 civilians have been killed by bullets, grenades, and bombs, including numerous women, children, and young individuals" in areas between Uvira and the provincial capital, Bukavu.

The latest M23 offensive comes despite a US-mediated peace agreement signed last week by the presidents of Congo and Rwanda in Washington. The accord, however, did not include the rebel group, which is engaged in separate negotiations with Congo and had previously agreed to a ceasefire earlier this year, with both sides accusing each other of violations.

The agreement requires Rwanda to end support for armed groups and take measures to halt hostilities. The South Kivu government said, "Based on the information collected, the forces currently in the city consist of Rwandan special forces along with several foreign mercenaries, acting in blatant violation of the ceasefire and the agreements established in Washington and Doha, completely ignoring the commitments that were made."