Alpine skier Stefan Luitz of Germany is under investigation for allegedly breaking anti-doping rules by inhaling oxygen between runs during his giant slalom win at the International Ski Federation (FIS) Alpine Ski World Cup in Beaver Creek, U.S., last weekend.

The FIS said on Friday it was looking into the matter after Italian and Swiss journalists revealed the existence of a photograph which appeared to show the German inhaling oxygen.

In June 2016, the FIS banned the use of oxygen cylinders in competition, a point specified in the federation's anti-doping regulations.

Luitz and the other German skiers, who are also involved in the investigation, have not been suspended from competition.

"No team brought a claim after the giant (slalom) at Beaver Creek," FIS race director Markus Walder said. "The investigation is still ongoing."

Luitz, who had just returned to the slopes after a year out with injuries to claim his maiden World Cup win, now faces possible disqualification.

If that happens, victory in Beaver Creek would pass to Austrian ace Marcel Hirscher.

(Top image: Stefan Luitz of Germany skis the first run of the men's giant slalom at the FIS Alpine Ski World Cup in Beaver Creek, Colorado, U.S., December 2, 2018. /VCG Photo)