The controversy surrounding Jamaica’s anti-doping programme has intensified after the country’s most senior drug tester claimed recent positive tests could be the “tip of the iceberg”.

Five Jamaican athletes who were cleared after producing positive tests at their national trials in June are allowed to compete at the World Championships, although an independent panel hearing an appeal against the decision has yet to sit.

Four of the five Jamaican athletes who produced positive samples at their national trials in June are likely to hear their fate on Monday after their disciplinary hearings concluded yesterday.

The International Association of Athletics Federations (IAAF) tonight confirmed that five Jamaican athletes have tested positive for a banned substance.