Congolese troops are involved in joint operations with Rwandan forces
At least 40 Rwandan Hutu rebels have been killed in air strikes in the Democratic Republic of Congo, according to military officials.
The air raids, in the east of the country, came during a joint offensive by the Congolese and Rwandan armies.
A rebel commander, Edmond Ngarambe, is reported to have surrendered along with other rebel fighters.
The Congolese government has allowed Rwandan troops into its territory to pursue Rwandan rebels based there.
The numbers killed in the air raids - 75km west of the provincial capital Goma - make them the deadliest since the arrival of Rwandan forces in January.
One air strike was directed specifically at a meeting of rebel commanders belonging to the Hutu Democratic Forces for the Liberation of Rwanda (FDLR), some of whose leaders are accused of involvement in Rwanda's 1994 genocide.
In a separate development, campaign group Human Rights Watch has reported an increasing number of civilian deaths since Rwandan forces moved over the border into DR Congo's eastern provinces.
More than 100 civilians have been killed in the past three weeks, according to Human Rights Watch.
The group says Hutu rebels abducted some civilians to use as human shields, while others were hacked to death.
The report also says that FDLR fighters have raped more than a dozen women whom they accused of having joined the government side against them.
Human Rights Watch has again urged combatants not to attack civilians caught up in the latest fighting.
The presence of the FDLR in DR Congo is one of the factors in some 15 years of conflict in the region.
Rwanda has twice invaded its larger neighbour, saying it wants to stop the FDLR staging attacks from Congolese territory.
It had accused DR Congo of supporting the FDLR, before the two countries agreed to work together against all rebel groups in the area.