A total of five athletes - one from Kazakhstan and two from both Estonia and Austria - were detained as part of a targeted operation against a worldwide drugs network yesterday.

In a statement, the National Ski Racing Federation of Kazakhstan said four-time Olympian Alexei Poltoranin was among those arrested by Austrian police.

The governing body claimed it was "categorically against dishonest methods" and would defend Poltoranin until it is proven that the 31-year-old double World Championships medallist had violated anti-doping rules.

Estonia's ski federation said Karel Tammjarv and Andreas Veerpalu were detained alongside Poltoranin.

Veerpalu is the son of two-time Olympic gold medallist Andrus Veerpalu, who was initially banned by the FIS for three years before the Court of Arbitration for Sport acquitted him in March 2013 in a controversial case.

Austrian media reported the two athletes from the home country who were caught up in the doping raid were Max Hauke and Dominik Baldauf - both of whom are cadets in the Austrian police.

All five did not start the men's 15 kilometres cross-country classic race yesterday as a result of their arrests.

A video has since emerged reportedly showing Hauke being caught in the middle of a blood transfusion. 

Raids also took place in Erfurt in Germany in a coordinated operation involving both Austrian and German officials.

Two people were arrested there, one of whom is a doctor with reported links to doping in cycling.

The raids followed a recent documentary by ARD, in which Austrian skier Johannes Dürr, who was convicted of doping after the Sochi Olympics in 2014, confessed he had doped in Germany.

In the piece titled "Doping Top Secret: Confession, Inside the mind of a doper", Dürr revealed how he cheated, admitting to blood transfusions and taking EPO and growth hormones.

Dürr confessed to having his blood manipulated at hotels near Munich Airport and in other places across Germany including Oberhof and Irschenberg.

The World Anti-Doping Agency said it had helped provide information to the police amid their investigation which led to the raids, while the FIS said it was working closely with Austrian authorities.

Law enforcement in Austria are involved as the country treats doping as a form of financial crime.