LONDON -- Track and field's governing body is considering retesting drug samples from the World Championships to search for the designer steroid at the heart of a U.S. doping scandal.

The International Association of Athletics Federations said Monday it may reopen the estimated 400 urine samples taken during the Aug. 23-31 championships in France.

Any positive tests could lead to retroactive disqualifications and two-year bans.

IAAF general secretary Istvan Gyulai said officials were studying the legal implications before going ahead with new tests. He said a decision is expected early this week.

"We are for transparency,'' he told The Associated Press by telephone. "We want a clean sport. This is a great opportunity. We don't want to leave potential cheaters untouched.''

In potentially the biggest drug bust in sports history, the U.S. Anti-Doping Agency announced last Thursday that several athletes tested positive for a previously undetectable steroid -- tetrahydrogestrinone, or THG.

USADA chief executive officer Terry Madden called it a widespread conspiracy involving chemists, athletes and coaches.

UCLA's doping control laboratory developed a test for THG after an unidentified coach turned in a used syringe containing the substance. USADA retested 350 samples from the U.S. track and field championships in June at Stanford, Calif., as well as 100 samples from random out-of-competition tests.

The athletes who tested positive for THG haven't been identified pending analysis of their B samples. Some non-American athletes also are reportedly involved.

In a related development, up to 40 Olympic and pro athletes have been subpoenaed by a federal grand jury investigating a California company identified by USADA as being the source of the steroid.

Under the IAAF's drug-testing agreement with French authorities for the World Championships, all samples taken in France must be tested in France, IAAF spokesman Nick Davies said.

"They don't know how to test for THG in France,'' he said. "Los Angeles is the only one that can do it at the moment. But we might be in a position to test them in Los Angeles or Los Angeles could share the knowledge with the French lab.''

Dick Pound, chairman of the World Anti-Doping Agency, said the IAAF should proceed with the tests.

"I would think that the IAAF should be saying, 'To the extent we still have some samples around we should analyze them and make sure it wasn't being used at our championships,''' he said. "I think they ought to welcome the opportunity.''

IOC vice president Thomas Bach also supported the move to recheck the samples.

"As far as it can be done, why not?'' he said. "Paris is still very recent.''