Renewed fighting broke out Friday between government and rebel forces in the Democratic Republic of Congo, just days after peace talks were suspended.
The U.N. mission in Congo reports the sides clashed around Kimbumba, 15 kilometers north of the city of Goma. It says mortars and machine guns were used, and that 5,000 civilians have crossed the border into Rwanda to flee the fighting.
At the United Nations, Rwandan ambassador Eugene Gasana said a shell from the unrest had landed inside Rwanda.
In a VOA interview, he said his country would not continue to tolerate the unrest along its border.
"We asked them to go far, whoever it is. Whoever did it. We will not let them continue. We warned them already, the government, that they should go far away from our border, not to come and shell the bombs in Rwanda or anything. Otherwise, we will react immediately."
The Congolese army and rebel group M23 accuse each other of launching the first attacks.
Troops with the U.N. mission, known as MONUSCO, are reported to be standing by, ready to intervene if necessary. U.N. spokesman Martin Nesirky says MONUSCO has carried out aerial reconnaissance of the area.
High-level peace talks in Uganda between the government and M23 broke down on Monday, after the sides failed to reach an agreement on amnesty for the rebels and their reintegration into the armed forces.
M23 consists of rebel fighters who joined the Congolese army in a 2009 peace deal but later defected, saying they were treated poorly and the government did not live up to the deal.
Last year, the group took over territory in North Kivu province and briefly seized Goma, the provincial capital.
North Kivu and nearby provinces have endured years of fighting between the government and various militia and rebel groups. Much of the fighting is over control of the area's rich mines.
U.N. experts have accused Rwanda and Uganda of supporting M23, an allegation both nations deny.