(CNN) -- Rebels in an unstable part of the Democratic Republic of Congo have until Thursday afternoon to hand in their weapons to U.N. peacekeepers or risk being disarmed by force.
The ultimatum comes amid the latest flare up of unrest in central Africa's volatile Great Lakes region.
The 19,000-strong U.N. peacekeeping mission in the country, MONUSCO, issued the deadline on Tuesday. It's the first time it has said it will use its troops there to implement a security area around the city of Goma, by the border with Rwanda.
Sitting on the shore of Lake Kivu, the city has been at the center of clashes in the region over the past year between the M23 rebel group and Congolese government troops that have displaced more than 100,000 people, according to the U.N.
The rebels occupied Goma for more than a week in November before withdrawing amid pressure from regional leaders and the African Union.
But since mid-May, M23 forces have carried out repeated attacks on government troop positions "in an apparent attempt to advance on Goma and Sake," another nearby city, the U.N. mission says.
The rebels have used "indiscriminate and indirect fire, including by heavy weapons, resulting in civilian casualties" and attacks on U.N. installations, the peacekeepers say. The latest fighting has also reportedly drawn in a group of Uganda-based rebels.
If rebel troops in an area of North Kivu province that includes Goma and Sake ignore Thursday's deadline to give up their weapons at a U.N. base, "they will be considered an imminent threat of physical violence to civilians and MONUSCO will take all necessary measures to disarm them," the peacekeepers' statement says.
Those rebels who agree to hand in their arms will enter a process of demobilization and reintegration, the U.N. says.
A breakaway group
The M23 group was named for a peace deal of March 23, 2009, which it accuses the government of violating. The soldiers, mostly from the Tutsi ethnic group, became part of the national army through that accord.
However, they broke away from the Congolese army last year, complaining they weren't being promoted as promised, and because of a lack of pay and poor conditions.
The latest unrest continues a cycle of misery in the eastern Democratic Republic of Congo, a mineral-rich region at the epicenter of a political and ethnic conflict involving its neighbors to the east, Uganda and Rwanda.
Region in crisis
The humanitarian crisis in the region involves 2.6 million internally displaced people, the U.N. says, and 6.4 million people in need of food and emergency aid.
The area has been embroiled in violence since 1994, when ethnic Hutu forces crossed the border from Rwanda fearing reprisals after the genocide in that country.
At least 800,000 people in Rwanda were killed in the 1994 genocide, one of the worst mass slaughters in the post-World War II era.
The victims were mostly from the Tutsi ethnic minority, who were targeted by Hutus over a rivalry that dates to colonial days. Some moderates from the Hutu majority who supported Tutsis also were killed.