Defence Minister Lindiwe Sisulu's motorcade was stoned in the Democratic Republic of Congo according to a report.
Sisulu visited the DRC ahead of Monday's parliamentary and presidential elections, which had been marred by violence in the run-up to voting day.
Business Day reported that Sisulu's motorcade was attacked en route to Kinshasa's international airport on Saturday.
The Congo's envoy to South Africa, Bene M'Poko, confirmed to the daily that her motorcade was stoned and threatened by opposition supporters.
Two people have been killed in campaign violence.
President Joseph Kabila, 40, in power since 2001, is tipped to be re-elected. He faces opposition from Etienne Tshisekedi, 78, leader of the Union for Democracy and Social Progress.
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