The International Association of Athletics Federations has launched an inquiry into Kostas Kenteris and Katerina Thanou over missed drug tests.
The Greek sprinters were absent when testers showed up in Chicago and Athens to take mandatory random samples and later withdrew from the Athens Games.
But the IAAF said at its monthly meeting it will investigate the issue.
Kenteris and Thanou will be free to compete until the IAAF decides whether they have a charge to answer.
A three-man panel comprising of IAAF president Lamine Diack, senior vice-president Arne Ljungqvist and American lawyer Bob Hersch will compile all the evidence against Kenteris and Thanou, plus their coach Christos Tzekos.
They will then decide if it is sufficient to launch proceedings against them.
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It is our number one priority
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IAAF on the sprinters probe
Only then, when the case will be referred back to the Greek athletics authorities, would the sprinters be suspended pending the outcome of the hearing.
"Under IAAF rules, no athlete can be suspended until they have had a charge made against them formally and been given a right to a hearing," said IAAF spokesman Nick Davies.
"That is a basic principle of law.
"We are treating this case very serious and the review panel will start its work immediately.
"It is our number one priority and we will endeavour to conclude the case as quickly as possible."
The IAAF intends to have the inquiry and hearing, should one be called, completed by their next executive committee meeting, which will be held in December.