The Ugandan troop deployment comes as the Congolese army faces a major challenge from rebel groups seeking to control the mineral-rich region.

Uganda's army said on Tuesday that its troops would be deploying to the Democratic Republic of Congo (DRC) to help fight local militias.

The troops will be deploying to the town of Bunia in the eastern part of the DRC.

Why is the Ugandan military deploying in Congo?

Uganda's military accused militia groups of committing "massacres" in eastern Congo.

"There were massacres being committed by some militia groups and we agreed with our Congolese counterparts to carry out joint operations to save lives," Ugandan military spokesman Felix Kulayigye told AFP.

Uganda already had thousands of troops in the DRC's Ituri province, of which Bunia is the capital.

Ugandan troops had been there working alongside DRC forces against an Islamist group, the Allied Democratic Forces, which has been linked to the "Islamic State" group.

The head of Uganda's armed forces, Muhoozi Kainerugaba, gave rebel groups an ultimatum on Saturday.