Jones was in good form before a positive drugs test

The American sprinter was selected for the USA team but does not feel she is in shape to run following a month-long absence after a positive drugs test.

She was cleared to run again last week after her "B" sample for banned drug erythropoietin (EPO) proved negative.

"Unfortunately, I just don't feel that my race conditioning is there," Jones said in a statement.

"I was in top condition when my season was interrupted more than three weeks ago by the leak of my positive 'A' sample.

"I was ready but missed top August competitions in Zurich, Monaco and Brussels and it has been more than six weeks since I raced.

"I am honoured to have been selected to compete on the United States team but I have always said that if I am not ready to compete in top form, I won't get on the track."

Jones' initial sample at the USA Track and Field Championships on 23 June tested positive for the blood-boosting drug EPO.

Victory there automatically earned her selection for the World Cup meeting, but she has now withdrawn from that and what was to have been her final race of the season in Shanghai.