The International Association of Athletics Federations (IAAF) charged the sprinters this month for missing the drugs tests. Their former coach Christos Tzekos has also been charged with distributing prohibited substances and tampering with the doping control process.
The IAAF said on Friday it had received written explanations from Kenteris and Thanou.
"These explanations have been circulated to the IAAF's Doping Review Board," a statement 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."
The IAAF said Tzekos had been granted an extension of time to provide his explanation until December 21.
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Greek prosecutors last month charged the sprinters with repeatedly obstructing doping officials after they failed to appear at scheduled drugs tests in Chicago and Tel Aviv shortly before the Games, and again in Athens on August 12 on the eve of the opening ceremony.
They were also charged with faking a midnight motorcycle crash which led to them spending four days in hospital as the IAAF sought to question them. Some hospital staff were charged with writing up false medical reports.
The sprinters could face a ban of up to two years but under IAAF rules they could appeal against any decision of the Greek Federation to the Court of Arbitration for Sport (CAS).
Kenteris was a shock winner of the men's 200 metres gold medal at the Sydney Olympics four years ago and Thanou won the women's 100 metres silver.
The fall from grace of the two athletes, national heroes after their success in Sydney, was the biggest Olympic doping scandal since 100 metres gold medallist Ben Johnson tested positive for drugs at the 1988 Seoul Olympics.