A Democratic Republic of Congo spokesman said its army is fighting “a war against Rwanda” in the east of the vast country.
The comments, by Press and Information Minister Henri Mova, come after two days of fighting in the town of Kanyabayonga had left dozens dead.
Around 15,000 people in the town of Kanyabayonga have fled their homes to escape the fighting.
“Congolese troops have met resistance from Rwandans in Kanyabayonga,” said Mova. “This is not a mutiny, it’s a war against Rwanda.”
“Our soldiers are conducting a security operation in Nord Kivu after noting the presence of Rwandan troops” in eastern DRC, Mova said.
Rwanda responded immediately, with Kigali denying it has sent troops into DRC.
President Joseph Kabila announced early this month that 10,000 army reinforcements would be sent to the east, amid reports that Rwanda had deployed troops in its vast neighbour to the west.
Around 25 rebels have been killed and two Rwandan soldiers captured by the DRC army, according to Rwandan reports.
“On Sunday, we counted around a dozen dead on the rebel side and one dead and 16 wounded on the Congolese armed forces side,” said DRC spokesman Kasongo Kudura, confirming the toll.
“The army also took six prisoners, two of whom have been formally identified as and admitted to being Rwandan soldiers,” he said.
The army has been fighting heavily armed mutinous soldiers from its eighth military region who seized the eastern town of Kanyabayonga over the weekend.
Rwanda was one of a handful of African countries to send troops into DRC during its 1998-2003 war, which claimed the lives of an estimated 2.5 million people.
According to a recent report, 1,000 people continue to die each day in the former Belgian colony as a result of the war, mainly from disease and starvation.
The BBC reports the renegade soldiers are patrolling the streets of Kanyabayonga and have set up camp in mountains surrounding the town.