Greek sprinters Costas Kenteris and Katerina Thanou have been dope tested by doctors from the World Anti-Doping Agency, an official said on Tuesday.
The pair, charged by the International Association of Athletics Federations (IAAF) for missing drugs tests at this year's Athens Olympics, were among a group of Greek athletes to be tested on Sunday and Monday.
"The doctors showed us their IDs and inquired about several athletes including Kenteris and Thanou who they then tested," said an official at the Agios Kosmas training centre.
"They then wanted to know the whereabouts of some more athletes."
Kenteris and Thanou, who have until December 16 to file their defence to the IAAF, shocked the sporting world on August 12 after missing an eve-of-Games test. They voluntarily withdrew from the Olympics before competing.
Greek prosecutors last month also 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.
In the biggest Olympic scandal since Ben Johnson had his 1988 gold medal taken away for testing positive for drugs, Kenteris and Thanou 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.
WADA chief Dick Pound, in Athens for an international conference, predicted the pair would be found guilty of a doping violation.
"My prediction is that they (IAAF) are going to find that there was a doping violation and that there will be sanctions against the athletes and, I hope, against the coach," Pound told reporters in Athens.
Coach Christos Tzekos has been charged with distributing prohibited substances and tampering with the doping control process.