Six athletes were suspended on Thursday for five days by the International Ski Federation at the Nordic World Ski Championships in Sapporo, Japan due to high hemoglobin levels.

The high hemoglobin levels were detected in pre-competition blood testing. The suspended who will miss the first five days of the event, can compete in the Feb. 22-March 4 meet if they clear a second test, the federation said.

The Nordic world championships were to begin later Thursday with the men's and women's cross-country sprint races at Sapporo Dome.

The six athletes are Russians Voronin Konstantin and Dmitry Matveev and Italian Jochen Strobl in Nordic combined, along with cross-country skiers Alen Abramovic of Croatia, Sergei Dolidovich of Belarus and Reto Burgermeister of Switzerland.

The suspensions are not a punishment and but served to protect the health of the athletes, the federation said.