STAVANGER, Norway (AP) — Without naming names or providing any proof, a former Norwegian anti-doping official has claimed that several top athletes in the country engaged in blood doping in recent years.

Mads Drange, a former tester for Anti-Doping Norway, writes in his book Den Store Dopingbloeffen (The Great Doping Bluff) that the athletes must have been doping because they had exceptionally high variations in their blood profiles.

Although Drange would not say which athletes he was referring to, speculation has focused on winter sports, such as cross-country skiing.

"I don't want to create a witch hunt. It is just to show the system doesn't work because even here in Norway where there is a good testing regime it is easy to cheat," Drange told The Associated Press. "There is no testing in most countries in the world, or the testing is no good. People might talk about Jamaica or Kenya but you don't have to look any further than Europe."

Norway is one of the strongest countries in winter sports, and the publication of the book comes just ahead of the start of next month's Sochi Olympics.

Speaking after the book's release on Thursday, Drange said the variations in the blood samples could only have come about through doping. He said he was referring to the period from 2000-10.

"I couldn't find any other explanation for these results than blood doping," Drange said.

Anders Solheim, the head of Anti-Doping Norway and a colleague of Drange, denied the claim. He said the results could not be automatically linked to doping and that the agency would have prosecuted any athletes had they found sufficient evidence of illegal procedures.

"If we had received good enough evidence we would have prosecuted the athletes through the prosecution committee," Solheim said. "You need to have the evidence."

In recent years several sports have adopted the biological passport program, a system which monitors an athlete's blood profile over time to detect any signs of doping. Several athletes have been caught without failing a doping test.

Drange also criticized international anti-doping authorities for "failing to implement their own rules" and national agencies for not carrying out sufficiently rigorous tests before major international competitions for fear of what they might find.

"You have to be stupid to fail a test at a major tournament. So the chance that the clean athletes have for fighting for medals are a lot less than they could have been," Drange said. "The national associations have failed their clean athletes."