The Democratic Republic of Congo's M23 rebels said attacks on areas under the movement's control in the eastern part of the country may derail peace talks under way in Uganda's capital Kampala.
A second round of meetings were concluded on Tuesday. At the beginning of this week the M23 lauded the progress being made at the talks, but are now bemoaning the attack on their positions, which they accuse the Congolese government army FARDC of spearheading.
The United Nations peacekeeping and stabilisation force Monusco on Thursday reported renewed fighting in the North Kivu province between the M23 and the Congolese army.
Monusco's Alexandre Essome said fresh violence had erupted near the town of Mabenga, north of the North Kivu capital Goma.
While Monusco blamed M23 for causing the latest round of fighting, M23 claimed that a coalition of FARDC and some Mai Mai militias on Wednesday night attacked Mabenga-Kiwanja and Kinyandoni Ishasha, areas the movement controls.
"This is the way of the Congolese government to undermine the peace efforts undertook in recent days by the international community," said M23 chairperson Bertrand Bisimwa in a statement.
He added: "While reiterating our commitment to the Kampala process as the only way to resolve the crisis in our country, our army will defend the population living in our administered area against any threat."
M23 accused the FARDC of having a "warlike desire, which favours the bloodshed of our people" instead of resolving the stand-off that has turned eastern DRC into a warzone.
South African soldiers form part of the SADC intervention brigade that has been put together to help the Congolese army push rebels out of residential areas. The SADC forces were however not involved in this week's fighting, though they remain on standby.
The M23 earlier expressed hope that if the Great Lakes region, Monusco, the African Union and the European Union provided the requested political and technical support to the Kampala dialogue, an agreement would be reached soon.
The movement declared a unilateral ceasefire after just over a week of fighting last month. The M23 has since requested an independent investigation into that battle, claiming the movement was only trying to protect its positions.
A mutiny by FARDC soldiers early last year resulted in the formation of the M23 after members from disbanded rebel groups who were integrated into the army complained that Joseph Kabila's government had failed to implement key agreements of the peace talks that ended hostilities. Since then peace talks have repeatedly stalled.