FRANKFURT — A Der Spiegel news magazine report implicates German riders Andreas Kloeden and Matthias Kessler in illegal blood transfusions, citing the findings of an independent commission investigating doping.

The commission spent two years looking into doping allegations against two doctors who allegedly put a doping system into place at Freiburg University Clinic between 1995 and 2006 for the former Team Telekom, later known as T-Mobile.

Doctors Lothar Heinrich and Andreas Schmid, fired by the university in 2007, have admitted providing and administering doping material until 1999. But the commission concluded they continued until at least 2006, the news magazine reported.

Kloeden and Kessler are suspected of receiving illegal transfusions of their own blood in July 2006, along with teammate Patrik Sinkewitz. All were assisted by one of the two doctors, according to the report.

Kloeden, who now rides for Astana, has always denied doping.

Astana team spokesman Philippe Maertens said Kloeden again denied any wrongdoing.

"We spoke to Kloeden about the allegations, and he's repeated that he had nothing to do with the whole thing," Maertens said.

Sinkewitz tested positive for testosterone in an out-of-competition test before the 2007 Tour de France. He was banned for one year, half the usual suspension, because he cooperated with German investigators and gave details about doping in cycling.

Former Astana rider Kessler was banned for two years in January 2008, eight months after the team suspended him when a sample showed elevated testosterone levels after a surprise test.

Hans Joachim Schaefer, a lawyer who leads the commission, declined to comment on the report Sunday.

"I have sworn to myself that I won't say a word," he said.

The commission's 64-page report is expected to be published soon.