On Tuesday, a DRC security official who asked for anonymity said war planes were bombarding the rebel-held Tchanzu area of North Kivu and would continue "all day".
A resident of the strategic town of Bunagana on the Ugandan border -- which the M23 captured in June -- confirmed to AFP that the aircraft were striking the area.
"It's every man for himself," he said, describing how town residents were fleeing across the border into Uganda.
Damien Sebuzanane, a local civil-society representative, also said that Bunagana residents had fled.
The DRC deployed two Sukhoi-25 jets to the troubled east over the weekend, after the M23 captured a series of settlements along an important highway leading to Goma.
One of the planes violated Rwandan airspace on Monday -- although Kinshasa said the incident was a mistake and not intentional.
A mostly Congolese Tutsi group, the M23 first leapt to prominence in 2012, briefly capturing the main city in eastern Democratic Republic of Congo (DRC), Goma, before being driven out.
After lying dormant for years, the group took up arms again in late 2021 claiming the DRC had failed to honor a pledge to integrate them into the army, among other grievances.
M23 rebels have won a string of victories against the Congolese army in North Kivu province in recent weeks, dramatically increasing the territory under their control.
Their resurgence has cratered relations between the DRC and its smaller neighbor Rwanda, which Kinshasa accuses of backing the M23.