GOMA, Congo — Clashes erupted Monday in the Democratic Republic of Congo between government troops and a rebel group believed to be backed by neighboring Rwanda, escalating to the use of mortars and rocket launchers in the first fighting between the groups since the M23 rebels overtook and later retreated from the provincial capital of Goma last year.
Fears that the rebels will try to retake Goma have been mounting since the UN Security Council created an intervention brigade with a mandate to attack the armed group.
The M23 called the creation of the brigade a ‘‘declaration of war.’’
Monday’s fighting forced thousands of people to flee, leaving behind deserted villages. Hundreds sat with their belongings packed at their feet near one barrier put up by a UN peacekeeping mission in Kanyaruchinya.
Alphonsine Ndahandi, a 63-year-old grandmother carrying her family belongings in a bundle on her back, said the fighting began at 4 a.m.
‘‘There were gunshots, bombs. It was raining on our village. It was much, much stronger than when they fought in November,’’ she said.
The clashes ‘‘escalated to the use of heavy-caliber weapons, mortars, and rocket launchers,’’ according to Eduardo del Buey, the deputy spokesperson for the UN secretary-general.
Lieutenant Colonel Mamadou Ndala, a commander with the Congolese military, said that the rebels opened fire on government troops near Muja, north of Goma, which is one of the most important cities in Congo’s east.
The M23 rebel movement is made up of soldiers from the Tutsi ethnic group, who defected from the Congolese army. The M23 on Monday denied that they had attacked the military and said that Congo’s army had opened fire.