Five Jamaican athletes - including two London 2012 medallists - have tested positive for banned substances, according to the Jamaican newspaper the Gleaner.
Two field and three track athletes reportedly tested positive for the banned substances following recent tests at Jamaica's National Stadium.
The paper reports that two of the runners who allegedly tested positive for the banned substances won medals at the Olympic Games in London.
The Jamaican Anti-Doping Agency said it had not received any independent verification of the adverse findings.
The revelations, a month ahead of the World Championships, come after the American sprinter Tyson Gay revealed he had tested positive for a banned substance.