The Greek sprinters were charged by the International Association of Athletics Federations (IAAF) after missing tests in Tel Aviv, Chicago and Greece.
However, according to a source they rejected the claims in letters to the IAAF and an investigation is now under way.
A statement by the IAAF said: “Following a careful review of all the documents, the Doping Review Board will reach its decision as to whether the explanations are acceptable in the next few days.
“If the explanations are unacceptable, in accordance with IAAF rules, the athletes will be provisionally suspended pending a hearing before a disciplinary tribunal in Greece.”
Under IAAF rules Kenteris and Thanou could receive a maximum one-year suspension.
The IAAF issued an official warning last year after the pair, and coach Christos Tzekos, were found to be training in Qatar rather than Crete as they had told Greek athletics officials.
There was also a missed test in Tel Aviv and then shortly before the Games they missed a test in Chicago when they decided to fly to Greece a day earlier than expected.
Athletes are required to inform their national federations of their exact whereabouts if they leave their usual home address, so that anti-doping officials are able to contact them if they wish to administer out-of-competition tests.
The pair have been under scrutiny since they were asked to attend a doping test on the eve of the Games in Athens, where Kenteris was set to defend his Olympic 200metres title. They missed the test after leaving the Olympic village and their whereabouts could not be determined until much later in the evening - by which time the International Olympic Committee (IOC) officials had departed.
They were eventually contacted but asked for extra time to return to the village - this was refused.
The World Anti-Doping Agency’s guidelines stipulate requests for a delay in taking tests must be declined if the athlete in question cannot be continuously chaperoned by a suitable official. Events took a further twist when they were involved in a mysterious motorcycle accident which, they claimed, happened as they were returning to the Olympic village.
They remained in the KAT Hospital in the capital for four days and after being discharged were suspended by their national Olympic federation. A criminal probe was launched and on November 18, after two months of preliminary investigations, the pair were charged by the Greek chief prosecutor with avoiding a drugs test on the eve of the Olympics and then faking a motorcycle accident.
A total of eight charges have been brought against the duo, their former coach Tzekos, eyewitnesses of the motorcycle incident and seven doctors from the Athens KAT Hospital.
Tzekos has been granted an extension to provide his explanation and must respond by December 21. He has also been accused of “distributing prohibited substances, assisting in the use of prohibited substances and tampering with the doping control process.”