Vienna, Austria: Austrian police said on Wednesday that they had carried out a series of arrests and raids along with police in Germany in a crackdown on an "internationally active doping network".
Some of the police action was centred on the Austrian resort of Seefeld, where the Nordic skiing world championships are currently in progress.
One Kazakh, two Austrian and two Estonian athletes are among those who have been arrested in the raids, Austria's Federal Criminal Police Office said in a statement.
Austrian police say the doping ring was based in Erfurt in 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".
Nine people were arrested in total and 16 properties searched as part of the crackdown, called "Operation Bloodletting" by police.
German prosecutors said in a statement that nine of the properties were in Erfurt.
They added that the police actions were sparked by revelations made by Austrian cross-country skier Johannes Duerr in a programme broadcast on German television in January.