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.
US sprinter Tyson Gay says he will pull out of next months's athletics World Championships after testing positive for a banned substance, according to the Associated Press.
The former 100m and 200m world champion reportedly said: "I don't have a sabotage story. I basically put my trust in someone and was let down."
Gay has run the fastest time in the world this year, clocking 9.75 seconds at the US World Championships trials last month.
American sprinter Tyson Gay says he has failed a dope test, Reuters are reporting.