Lewis, who won a silver medal in the 1997 World Championships, was due this weekend to defend her title in Gotzis, Austria, but she will now have to sit out until next month.
She should find out in the next 24 hours when she will be able to resume training. She said: "This is a blow coming so close to Gotzis. The season so far has built up well and I hadn't experienced any real difficulties in competition. But I've been in this situation before and I'm definitely not downbeat."
South Africa's Olympic 800 meters silver medallist, Hezekiel Sepeng, could miss next year's Sydney Olympics after failing to compete in the national championships earlier this year. His fate lies in the hands of a disciplinary committee of Athletics South Africa, who will meet the runner at a date to be set.
The pole vaulter Okkert Brits, who did not compete in the national championships either, is also expected to be present at the meeting.
Sepeng told the ASA that he would not be available for this year's world championships as he was concentrating on next year's Olympics. But according to the ASA's secretary general, Banele Sindani, the International Amateur Athletics Federation's regulations state that athletes who choose not compete in the world championships preceding an Olympics is ineligible for the Games.
The ASA announced a preliminary squad of 43 from which the final team for the Seville world championships in August will be selected. Included in the squad are the world and Commonwealth Games javelin champion Marius Corbett, the world indoor 800 metres champion Johan Botha, and the former world half marathon champion, Elana Meyer.