South Africa's military said on Wednesday that a mortar attack on one of its bases in eastern Democratic Republic of Congo a day earlier had killed two people and injured 20 others.

South African troops are in Congo as part of a deployment by Southern African regional bloc SADC to help the government fight rebel groups.

"Four members who were critically injured have been hospitalised, whilst the rest who suffered minor injuries are expected to be discharged soon," the South African National Defence Force said in a statement.

In February another mortar attack on a South African base in Congo killed two and wounded three others. At the time President Cyril Ramaphosa hit back at opposition criticism that the South African contingent in Congo was ill-equipped.