Islamic State group-linked ADF rebels have killed at least 21 people this week in the conflict-riven eastern Democratic Republic of Congo, local sources told AFP on Saturday.

The attacks all took place close to Manguredjipa, a town known for its rich mineral deposits and regularly targeted by the ADF.

On December 21, ADF rebels made an incursion into the village of Robinet, in the Bapere sector of North Kivu province, a local official said.

"They killed six people on the spot, then on December 22 they arrived at the neighboring village we call Kodjo where they killed 12 people," Macaire Sivikunula, a representative for the Bapere sector's governor, told AFP.

Then on Christmas Day, ADF fighters "arrived seven kilometers from Manguredjipa in the village called Makele and killed three people," Sivikunula added.

Multiple separate local sources confirmed the dates, locations and tolls of these attacks to AFP.

Originally from Uganda, the ADF, or Allied Democratic Forces, have been present since the mid-1990s in the DRC's restive northeast, where its fighters have killed thousands of civilians.

In 2019, the ADF pledged allegiance to IS.

The IS touts them as its Islamic State Central Africa Province and claims responsibility for some of the rebel group's attacks.

At the end of 2021, Uganda and the DRC launched a joint military operation against the ADF.

That offensive has so far proven unsuccessful in putting an end to the rebel attacks.

Both armies have pushed the rebels back into remote and inaccessible areas, where local civilians are often at their mercy.

Sivikunula said the Ugandan and Congolese armies were present and at work in Manguredjipa.

"But as the rebels are scattered in small groups of dispersed fighters, it's really difficult to pinpoint their location," he added.

North Kivu province also faces a separate rebel insurgency further south, with the Rwanda-backed M23 movement and the DRC's army locked in fighting all week following the failure of a peace summit in mid-December.

Home to vast mineral resources, the eastern DRC has been plagued by infighting between various armed groups for decades.