South Africa wants an investigation into a "disturbing" video allegedly showing one of its soldiers present while bodies were being burned on a pile of rubble in Mozambique, President Cyril Ramaphosa's spokesperson said.

South African soldiers are part of a Southern African regional force helping Mozambique fight an Islamic State-linked insurgency that has claimed thousands of lives since 2017.

The video went viral on social media this week, prompting a statement from the South African National Defence Force that the incident was believed to have happened in November 2022 and anyone found guilty of the acts seen in the clip would be punished.

Reuters has not been able to verify the contents of the video.

The Southern African regional force SAMIM has launched an investigation.

"We are anxious to understand what really happened," Ramaphosa's spokesperson, Vincent Magwenya, told reporters on Thursday.

Amnesty International said on Thursday that security in Mozambique's northern Cabo Delgado province, where the insurgency is concentrated, "must not come at the cost of human rights violations".

It said the video "gives a glimpse of what is going on ... in this forgotten war".

The Mozambican government has yet to comment on the video.

Hage Geingob, Namibia's president and the current chair of the Southern African Development Community's politics, defence and security organ, said this week that the regional bloc would take measures in line with the law of armed conflict once the investigation is complete.