Congolese army forces on Sunday killed 10 rebels of the Allied Democratic Forces (ADF) in the troubled east of the country, a spokesman said.
The offensive kicked off last Thursday in North Kivu and Ituri provinces, with army and police officers assigned to replace civilian authorities under a 30-day "state of siege".
In a clash in Halungupa, in the Rwenzori area, "our troops got the better of the ADF enemy. We in fact saw 10 dead bodies of ADF elements," Antony Mualushayi, army spokesman in the North Kivu city of Beni, told AFP.
The death toll is provisional, he added.
"We are determined to finish with the ADF once and for all," he said. "This siege should give the people of the Beni region the chance to live in a place where peace rules."
A spokesman for a monitor called the Kivu Security Tracker (KST) said however that it had counted "only five bodies so far".
Meanwhile a delegation of Ugandan officers arrived in Beni on Sunday, according to an AFP reporter, while the army and government authorities declined to comment on the visit.
The ADF, a group of Ugandan Islamist fighters, have been based in eastern Democratic Republic of Congo since 1995.
Branded a "terrorist" organisation affiliated with the Islamic State group by the United States, the ADF has been accused of murdering more than 1,000 civilians since November 2019 in Beni alone.
It is by far the most dangerous of scores of armed groups that operate in the east of the DR Congo.
Mineral-rich North and South-Kivu, which lie along the DRC's eastern borders with Uganda, Rwanda and Burundi, descended into violence during the country's two wars between 1996 and 2003, and have never regained stability.
Ituri, further to the north, has also been rocked by violence since late 2017 after 15 years of relative calm.
Under the DRC's constitution, the president can declare a state of either siege or emergency "if severe circumstances immediately threaten the independence or integrity of the national territory, or if they interrupt the regular functioning of institutions".