The former Aqua Blue Sport rider Stefan Denifl has confessed to blood doping in a police interview, according to reports.

Denifl, the winner of Aqua Blue’s only Grand Tour stage, was arrested in connection with a long-running investigation, Austrian media reports.

The public prosecutor said the 31-year-old had confessed to blood doping in a hearing last Friday, says Austrian newspaper Tiroler Tageszeitung.

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Denifl’s arrest is linked with the investigation into a German sports doctor, after recent police raids around doping in cross-country skiing.

The scandal began to unravel last week, when police raided 16 properties and arrested nine people in connection with blood doping in the Nordic skiing World Championships in Austria.

A number of skiers were arrested, alongside a German doctor who was linked to the former Gerolsteiner cycling team.

Video footage emerged after the raids, showing Austrian skier Max Hauke allegedly being interrupted by police in the middle of a blood transfusion.

While investigating the doctor police encountered Denifl, according to Austrian media.

Denifl started his career with Pro Continental team Vorarlberg in 2006.

In 2013 he joined IAM Cycling, and then moved to Aqua Blue Sport in 2017 for two seasons before the team collapsed last year.

He was due to move to the new CCC Team for 2019, but missed the outfit’s training camp last December due to “personal reasons.”

Later that month, CCC announced that Denifl and the team had mutually agreed to terminate his contract at the rider’s request, again due to personal reasons.

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Denifl won three pro races during his career, the biggest of which came at the 2017 Vuelta a España when he won in the mountains on stage 17 – the victory was Aqua Blue’s only Grand Tour victory.

According to the World Anti-Doping Agency, there are three main types of blood doping – EPO, synthetic oxygen and blood transfusions.

The techniques increase an athlete’s red blood cell mass, allowing the body to transport more oxygen to the muscles to improve stamina and performance.

Denifl has not yet spoken publicly about the investigation.