A Congolese-Ugandan military offensive against the deadliest militia in eastern DR Congo has captured 34 rebels, freed hostages and destroyed camps, the two armies said on Saturday.

Uganda and the DRC launched artillery and airstrikes on November 30 against the Allied Democratic Forces, a group blamed for attacks in the Ugandan capital and regular massacres in eastern DR Congo, with Ugandan troops then entering Congolese territory.

A joint army statement on Saturday said the operations captured 34 ADF rebels, released 31 Congolese hostages and destroyed four enemy camps in "preliminary results", noting no army deaths.

"Since the launch of operations against the ADF terrorists and their local auxiliary forces, the situation remains calm on the ground," the statement added.

The announcement came as the International Committee of the Red Cross on Saturday said two of its workers abducted in eastern DRC last month had been freed.

Armed men from an unidentified group kidnapped the Red Cross engineers on November 30 near the Virunga National Park, but the circumstances surrounding their liberation are unclear.

"We are relieved about the return of our colleagues and we are delighted they can rejoin their families. It's the end of their ordeal," Rachel Bernhard, head of the Red Cross delegation in the DRC, told AFP.

"This kidnapping and any attack against humanitarian staff can endanger activities aimed at helping communities who are already severely affected by the conflict."

6,000 dead  

The Islamic State group has claimed the ADF, which has operated in the conflict-wracked eastern DRC since the mid-1990s, as an affiliate. Numerous other armed groups are also based in the region.

The DR Congo's Catholic Church says the ADF has killed around 6,000 civilians since 2013.

Congolese President Felix Tshisekedi placed the eastern provinces of North Kivu and Ituri under a "state of siege" in May to intensify the battle against the rebels, with soldiers replacing civil servants in key positions.

The Congolese and Ugandan armies said they were carrying out road construction and rehabilitation works to secure the movement of soldiers and displaced civilians.

Uganda has accused the ADF or a local group affiliated with it of carrying out or planning a string of attacks this year.

On November 16, four people were killed and 33 wounded in twin suicide bombings in Kampala. Police blamed the blast on a "domestic terror group" that it said was linked to the ADF.

Since April 2019, some ADF attacks in eastern DR Congo have been claimed by IS, which describes the group as its Islamic State Central Africa Province offshoot.

In March, the United States placed the ADF on its list of "terrorist" organisations linked to IS.