The regional force fighting militant Islamists in Mozambique is carrying out an investigation after a video surfaced online showing people wearing what appear to be South African army uniforms setting ablaze corpses.
Two soldiers are captured throwing a body on to the side of a bonfire of burning rubbish including furniture.
The South African army said anyone involved would be “brought to book”.
Its forces were deployed to northern Mozambique two years ago.
They operate under the auspices of the Southern African Development Community Mission in Mozambique (Samim).
The undated video shows two men in army fatigues holding mobile phones appearing to be filming the fire, one of them has a badge with the South African flag on his uniform.
It also captures one of them throwing a liquid over a human body and the flames spread, a pot is also flung into the pile.
In a statement, the South African National Defense Force (SANDF) said the commander of Samim was “conducting an investigation surrounding the involvement of its members in this despicable act”.
“The SANDF does not condone in anyway the acts committed in the video” adding that those found guilty would be punished.
The army said the incident was believed to have taken place in November in Mozambique.
South Africa’s opposition Democratic Alliance (DA) party said the incident was as an “embarrassment” for the country and called for a government investigation.
The BBC’s Jose Tembe reports from Mozambique’s capital, Maputo, that the government there has not yet commented on the video.
Some people who have seen the footage have reacted with shock, saying those behind the “horrible” incident must be held responsible, he says.
However, he reports that others said they doubted it had happened in the country.
Mozambique has been battling IS-linked Islamist militants in its gas-rich northern province of Cabo Delgado province since 2017.
The violence has killed thousands and displaced hundreds of thousands from their homes.
A joint offensive with regional forces, including soldiers from Rwanda, has enabled the government to regain control over much of the region but it has not stopped attacks by the militants.