More than 37,000 people have been forced from their homes in the Democratic Republic of Congo over the last four days of fighting, according to aid agencies.
Local media report that the national army has retaken some areas that had been seized by the M23 rebels in recent days.
But the main road between Rutshuru and the North Kivu regional capital, Goma, remains blocked by the M23.
The DR Congo government has again accused Rwanda of supporting the rebels, which the government in Kigali denies.
Earlier this week, Rwanda called for a regional investigation into how some artillery fire crossed into its territory, injuring some Rwandans.
On Wednesday, a police chief in Goma asked locals to take up arms and defend themselves against the M23.
The rebels have released a statement protesting that such comments are a recipe to create ethnic tensions.
The M23, made up of mainly Congolese ethnic Tutsis, is one of more than 100 militia groups fighting the government in the resource-rich eastern DR Congo.
The rebels accuse the government of failing to honour an agreement to allow them to form a political party, have their fighters integrated into the national army and allowing refugees to return home.