World and Olympic 100m champion Justin Gatlin will face a lifetime ban from athletics if his positive test for testosterone is confirmed by the American authorities, the IAAF confirmed on Sunday.
"If USADA (the American anti-doping agency) confirms the violation, the sanction laid down by the rules of the IAAF is supension for life," said a statement.
Gatlin, the joint holder of the world 100m record, said Saturday that he had failed the test in Kansas in April.
It was the second positive test of his career.
The 24-year-old Gatlin also tested positive for the amphetamine Aderall at the 2001 US junior championships at the University of Tennessee.
A subsequent ban was overturned after it was discovered the substances were part of the medication he had been taking to combat attention deficit disorder.
"The IAAF can also confirm that Gatlin has agreed to attend a hearing before the USADA Review Board which is expected to take place shortly," added the IAAF statement.
IAAF President Lamine Diack said he was saddened by the Gatlin case.
"Although it is a matter of deep regret that one of the biggest stars of our sport is facing serious doping charges, I would take this opportunity to emphasise the IAAFs total commitment to the fight against doping," said Diack.
"In order to defend the credibility of our sport, we will engage all our efforts, in co-operation with partners such as USADA, to defend the majority of athletes who are clean, against those who break our anti-doping rules."
The IAAF added that Gatlin would also be stripped of his world record which he shares with Jamaica's Asafa Powell at 9.77sec.
"If the test is confirmed, he loses everything he has done since the date of the test," IAAF spokesman Nick Davies told AFP.
Gatlin equalled Powell's mark on May 12 in Doha; he tested positive in Kansas on April 22.
He would also lose the American 100m title he won on June 23.
But he will keep his medals from the 2004 Olympic Games - 100m gold, 4x100m silver and 200m bronze - as well as his world 100m and 200m titles from 2005 and world indoor title from 2003.