The Congolese army says it has killed 20 fighters from the M23 militia group and lost two soldiers in clashes with the rebels near the border with Uganda.
General Leon Mushale says a further 25 rebels were either captured or surrendered while six soldiers have been injured.
Mushale, who heads military operations in North Kivu province, says some of the rebels have fled to Uganda and Rwanda.
M23 is a mostly ethnic Tutsi rebel group that mutinied against the Democratic Republic of Congo in 2012, saying a peace accord signed in 2009 had not been respected by the government.
The militia was defeated the following year, but still poses a threat to peace and security in the country’s eastern region.