Anti-doping authorities in Jamaica say backup doping tests have come back positive for former 100-metre world record-holder Asafa Powell, teammate Sherone Simpson and three other island athletes.
The Jamaica Anti-Doping Commission made the announcement on Friday.
It says all the athletes have been notified.
JADCO says it will refer the findings to the Jamaican Anti-Doping disciplinary panel and hearings will be scheduled.
The agent for Powell and Simpson did not immediately respond to an email seeking comment.
Meanwhile, local media say a Jamaican disciplinary panel is deliberating after a four-day hearing on a positive doping test by three-time Olympic gold medallist Veronica Campbell-Brown.