Local sources reported that M23 rebels have taken control of several villages in eastern DR Congo after fighting with government troops in the Rutshuru region.

According to one source in the reserve, there were severe skirmishes surrounding the Virunga National Park, a UNESCO-listed world heritage site home to endangered mountain gorillas.

The source reported that the front line was at Matebe, Rutshuru, North Kivu province.

"The M23 rebels occupy Gisiza, Gasiza, Bugusa, Bikende-Bugusa, Kinyamahura, Rwambeho, Tshengerero, Rubavu, and Basare" and still held Runyoni and Tchanzu, said Nestor Bazirake, the spokesman for a group of villages in nearby Jomba.

Government troops held Bunagana and the Rwanguba bridge, but locals had already gone across the border to Uganda or neighboring DR Congo provinces, according to him. 

Read more: 30 killed in attacks in eastern DR Congo

Neither military sources nor regional officials could be reached for comment.

After many days of relative calm, fighting between rebels and soldiers erupted on Wednesday. Tens of thousands of people have already fled the region as a result of previous confrontations.

The M23 was formed by former members of a Tutsi militia in Congo that was originally supported by Rwanda and Uganda.

The rebels were absorbed into the Congolese army as part of a peace agreement reached on March 23, 2009.

They mutinied in 2012, claiming that the agreement had not been upheld, and renamed their group the March 23 (M23) Movement.

The M23, one of the numbers armed factions roaming eastern DR Congo, temporarily took Goma before being defeated and pushed out of the nation.

Following its defeat, the M23 negotiated an agreement with Kinshasa that contained measures for its fighters' reintegration into civilian society.

However, the group has accused the government of breaching the agreement once more, and combat restarted last year.

Read more: Dozens killed in an attack in DR Congo