The pair, and former coach Christos Tzekos, had until yesterday to reply to allegations of deliberately violating drug regulations.
Kenteris and Thanou are accused of missing out-of-competition drug tests in Tel Aviv, Chicago and Athens. They were also charged with avoiding a drug test on the eve of the Athens Olympics. The pair were withdrawn from the Games by the Greek authorities.
It also resulted in the IAAF appointing a doping review board which announced it believes evidence does exist of doping violations. If found guilty, a two-year suspension is almost certain to be imposed.