South Africa often uses its diplomatic heft to position itself as defender of the "global south" on the world stage, but the deaths of 13 of its soldiers in eastern Congo fighting have exposed an inability to project hard power in its own backyard.

M23 rebels fighting the Congolese army in eastern Congo are using advanced weapons and equipment similar to those used by the Israeli army and US special forces, a retired South African army general said Tuesday.

Four more South African soldiers have been killed in fighting with M23 rebels in the Democratic Republic of Congo, the government said, taking the number of South African peacekeepers killed to 13 since the conflict escalated last week.