The 23-year-old failed a test that showed elevated levels of haemoglobin in his blood and has not been allowed to start in the 15 kilometres freestyle cross country event and and the individual sprint classic.

Dr Perry Turner claimed that the failed haemoglobin test was because of a combination of altitude training and dehydration.

Koons recorded an increased haemoglobin level of 17.2g a decilitre in a standard pre-competition test on Sunday (February 14).

The accepted safety limit permitted by the International Ski Federation (FIS) is 17g a decilitre.

High haemoglobin values can be the result of athletes using banned substances, including the blood booster erythropoietin (EPO), but Turner claimed that is not the case in this incident.

He said: "Ben had his own blood test taken early this week and in his independent test he was significantly underneath, but on the upper limit of normal.

"Ben's been training in low atmospheric oxygen conditions at altitude the last few weeks, and that recent altitude training plus mild dehydration has resulted in a fractionally higher haemoglobin level over the maximum.

"Even with variations in your day and hydration levels [the haemoglobin level] can change."

Koons is barred from competing for five days.

Turner said that as the level of haemoglobin in blood went up, blood became more viscous.

He said: "That puts athletes at risk of cardiac events and stroke especially becoming dehydrated during the race.

"[The FIS] come up with this figure to keep athletes safe."

Koons, who is making his Olympic debut, will need to pass a fresh test before he can be cleared to compete in the 30km pursuit on February 20 and the 50km mass start classic on February 28, all to be held at Whistler Olympic Park.

New Zealand's Chef de Mission Peter Wardell also backed Koons.

He said: "He has made significant improvements in his performance over recent months and it's terribly disappointing for the young athlete.

"It is important to remember, however, that these rules are made to protect athletes' health and well-being."

Koons, though, will be encouraged by the news that Russian nordic combined competitor Niyaz Nabeev and Estonian cross-country skier Kaspar Kokk, both prevented from competing in events earlier this week because of failed haemoglobin tests, have now passed second tests and will be allowed to take part in the rest of the Olympics.

Contact the writer of this story at [email protected]


Related stories
February 2010: Skiers miss events after testing positive for high haemoglobin