0710 GMT October 19, 2019
Austrian and German police conducted a coordinated action against what they describe as an "internationally active doping network", BBC wrote.
The raids centered on the Austrian resort of Seefeld, which is hosting the Nordic World Ski Championships.
One Kazakh, two Austrian and two Estonian athletes have been arrested, a statement by Austria's federal criminal police office confirmed.
Austrian police said the alleged doping ring was based in Erfurt, Germany, and is "strongly suspected of carrying out blood doping of elite athletes in order to improve their performances in national and international competitions and to gain illegal profit from this".
Sixteen properties were searched on Wednesday, nine of which German prosecutors said were in Erfurt.
They added that a 40-year-old sports doctor, who was arrested in Germany on Wednesday, is believed to be at the center of the organization, and the action was prompted by claims by Johannes Duerr in a documentary called ‘The Greed for Gold’, which was broadcast in January.
The Austrian cross-country skier, who was convicted of doping after the 2014 Sochi Olympics, admitted to having blood transfusions, as well as taking EPO and growth hormones, at several places in Germany.
German journalist Hajo Seppelt contributed to the ARD documentary, and his previous work helped expose the Russian doping scandal.