Eufemiano Fuentes, the Spanish doctor accused of running an extensive blood-doping network, had contacts in France and Germany, doping expert Werne Franke charged on Sunday.
"The Spanish investigation files mention houses in France and Germany that were involved in the doping," Franke said in Focus magazine.
Former Olympic champ and Tour de France winner Jan Ullrich is alleged to have been given EPO and other banned substances by Fuentes, who was accused of running a blood-doping ring.
The 32-year-old Ullrich has repeatedly denied all doping allegations and says he does not know Fuentes.
The Swiss cycling federation has already announced proceedings against Ullrich; the German lives in Switzerland and has a Swiss cycling license.
Ullrich could face a life ban if found guilty as he is a second-time offender. He was caught using the recreational drug ecstasy a few years ago.
Germany eyes anti-doping law
Peter Danckert, chairman of the German parliamentary sports commission, said Sunday that there was a strong possibility that an anti-doping law could be introduced in Germany by the end of this year.
"That is my big aim and I believe we are very close to it," SPD politician Danckert told the Welt am Sonntag.
Danckert also said that there would be a meeting in the German parliament on September 27 with Minister of the Interior Wolfgang Schaeuble and Richard Pound, chief of WADA (World Anti-Doping Agency) attending.
The move follows the doping investigation into German cyclist Tour de France winner Jan Ullrich, who was forced to withdraw from this year's Tour de France on the eve of the race and subsequently sacked by his T-Mobile team.