JOHANNESBURG -- South Africa's track and field body says Tsholofelo Thipe and Rapula Sefenyatso have tested positive for a banned substance.
Thipe became the first black woman to compete for South Africa on the track in the Olympics, running in the 400 meters at the 2008 Beijing Olympics. ASA says she failed a drug test at the African Athletics Championships in Benin in June.
Sefenyatso, a men's 200-meter runner, also tested positive for doping.
It was not clear what substances the runners were allegedly using.
ASA president James Evans says "I don't know what is going on, but doping in South African athletics is becoming a serious problem."