The Democratic Republic of Congo has summoned Rwanda's ambassador and suspended Rwandair flights to Congo in response to what it says is Kigali's support for M23 rebels carrying out a military offensive in eastern Congo.
Rwanda denies supporting the rebels, who advanced as close as 20 km this week to eastern Congo's main city of Goma and briefly captured the army's largest base in the area.
Congo and U.N. investigators had also accused Kigali of supporting the M23 during a 2012-2013 insurrection that briefly captured Goma. Rwanda denied those charges.
Congo's government spokesman, Patrick Muyaya, announced the suspension of flights by Rwanda's national carrier and the summoning of the ambassador late Friday night, following a meeting of the national defense council.
He also said Congolese authorities had designated the M23 a terrorist group and would exclude it from on-and-off negotiations being held in Kenya's capital, Nairobi, between Congo's government and militia groups active in the east.
"A warning was made to the Rwandans, whose attitude is likely to disrupt the peace process that is nearing its end with the discussions in Nairobi, where all the armed groups, except for the M23, are committed to the path to peace," Muyaya said.
Rwanda's government was not immediately available for comment on Saturday.
The fighting over the past week has forced more than 72,000 people from their homes, the United Nations said on Friday, compounding Africa's worst displacement crisis.
Eastern Congo has experienced near constant conflict since 1996, when Rwanda and other neighboring states invaded in pursuit of Hutu militiamen who had participated in the 1994 Rwandan genocide