The first part of the Burundian troops pledged to deploy to the volatile eastern Democratic Republic of Congo (DRC) arrives in Goma.
The seven-nation East African Community began deploying troops late last year in the eastern DRC, which has been struggling with the rise of militias including the rebel March 23 Movement (M23).
The fighting in North Kivu province has displaced huge numbers of people and exacerbated regional tensions, with the DRC government accusing Rwanda of backing the M23 -- claims denied by Kigali but supported by the US and several Western nations.
The militia re-emerged from dormancy in late 2021, subsequently occupying swathes of territory in North Kivu, including much of the region north of its capital Goma.
The EAC, which has held several meetings to defuse the crisis and called for the withdrawal of the M23 from occupied areas, created a regional force aimed at stabilising the eastern DRC.
But thousands demonstrated in Goma last month, accusing the EAC force of passivity in the face of armed groups.
The troops will be deployed in Kitshanga and Kilorirwe -- areas occupied by the M23 in North Kivu -- as well as Sake, he said on condition of anonymity.
An EAC press statement on Friday confirmed Burundian troops would be deployed on Saturday, but did not elaborate on the number of soldiers travelling to the DRC.
According to a new timetable adopted by East African leaders last month, "all armed groups", including the M23, must withdraw by March 30, following a three-step process that was due to start on February 28.
- Border shooting -
The crisis has led to a sharp deterioration in ties between Kigali and Kinshasa.
In an incident along the tense border between the two nations, Rwanda's defence ministry said that a soldier from the Congolese armed forces (FARDC) "crossed over from DRC" on Friday evening and shot at Rwandan soldiers manning the area.
"The RDF soldiers returned fire, killing the FARDC soldier on the Rwandan side of the border," the statement said.
"Several other FARDC soldiers fired at the RDF position resulting in a brief exchange of fire," it added.
There was no immediate response from Congolese officials to the report, which follows similar incidents along the border in June and November last year.
The regional force is expected to include soldiers from Burundi, Kenya, South Sudan and Uganda. But its total intended size remains unclear.
Rebel militias have plagued the eastern DRC for decades, many of them a legacy of regional wars that flared during the 1990s and the early 2000s.
Some 5.5 million people were displaced within the country as of last November, according to the UN agency.
In addition, more than one million had left for a neighbouring country, with more than 500,000 seeking shelter in Uganda alone.