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.

"I'm giving exactly 24 hours for all forces in Bunia to surrender their arms! If they don't we shall consider them enemies and attack them," Kainerugaba posted on the platform X. 

Also on Tuesday, the Reuters news agency cited various military and diplomatic sources as saying that Burundi was withdrawing its forces from eastern Congo, where they had been adding Congolese troops in the fight against M23.

Where are rebels advancing in Congo?

The deployment of Ugandan troops to eastern DRC comes as the Congolese army faces a major challenge from the Rwanda-backed M23 rebel group.

M23 is the most prominent of more than 100 armed groups currently vying for control of the eastern Congo, a mineral-rich region, critical for global technology, worth trillions of dollars in wealth.

On Tuesday, M23 appeared to be heading toward the eastern Congolese city of Butembo, a little over two weeks after they captured the regional hub of Goma.

The rebels have also seized another provincial capital to Goma's south, Bukavu, near Burundi.

UN rights chief accuses M23 of rights abuses

On Tuesday, the UN human rights chief Volker Turk accused the Rwanda-backed rebels of killing children and attacking hospitals and warehouses storing humanitarian aid.

In a statement, Turk said that his office "confirmed cases of summary execution of children by M23 after they entered the city of Bukavu last week. We are also aware that  children were in possession of weapons."

UN agencies have previously accused both the rebels and Congolese government forces of recruiting children.

Edited by: Saim Dušan Inayatullah