Tom Dumoulin said he “felt betrayed” by the revelation his former team-mate Georg Preidler was involved in a blood doping ring.
Austrian pro Preidler resigned from Groupama-FDJ earlier this month after admitting he had extracted blood with the intention of doping.
Preidler, a former Sunweb rider, admitted he planned to dope after a police investigation into endurance skiing uncovered links to pro cyclists.
Sunweb’s Grand Tour favourite Dumoulin said the revelations show doping has not been eradicated.
The 28-year-old told Dutch broadcaster NOS: “My first reaction? I thought it was terrible, I felt betrayed.
“He says he didn’t do it with us, that he only did it last year.
“It shows that it hasn’t disappeared yet.”
Dumoulin and Preidler rode together for Giant-Shimano, which later became Sunweb, for five seasons before the latter moved on to French outfit Groupama-FDJ in 2018.
Preidler was part of Dumoulin’s 2017 Giro d’Italia winning squad.
The scandal began to unravel at the end of February, when police raided 16 properties and arrested nine people in connection with blood doping in the Nordic skiing World Championships in Seefeld, Austria.
Police operations were carried out in Seefeld and in Erfurt, Germany and 40 blood bags were seized.
A number of skiers were arrested, alongside German doctor Mark Schmidt who was linked to the former Gerolsteiner cycling team.
Gerolsteiner folded in 2008 after a number of doping scandals.
Video footage emerged after the raids, showing Austrian skier Max Hauke allegedly being interrupted by police in the middle of a blood transfusion.
The first cyclist caught up in the affair was former Aqua Blue Sport rider Stefan Denifl, who reportedly admitted to blood doping during a police interview after police uncovered his connection with the doctor.
Preidler then announced his “spontaneous and immediate” resignation to his Groupama-FDJ team on Sunday, March 3, having pulled out of the weekend’s racing.
The Austrian quit the team after he admitted to extracting blood to re-infuse it at a later date.
Marcel Kittel, who also rode for Argos-Shimano and grew up in Erfurt, said the doping revelations are a “slap in the face to clean athletes like him.”
The UCI has provisionally suspended both Preidler and Denifl.
Dumoulin added: “I am also very surprised I’ve been asked about it so little.
“Journalists have to keep this alive. I think it’s really important to remain sceptical.
“That is not always fun, but it is still happening.”