Doctors and athletes, including Olympic champions, are embroiled in an investigation by Austrian authorities into alleged illicit blood-doping, according to dpa. Austrian prosecutors confirmed Friday that the Federal Criminal Police Office (BKA) had begun a formal investigation after it received anonymous information regarding doping. "As the investigations have just begun, we cannot and should not say anything more," said a spokeswoman for Vienna's District Court. The BKA admitted Thursday that it had received the information but refused to comment on the status of the investigation. The Austrian APA newsagency reported that the anonymous letter contained information accusing 31 athletes, mainly from the field of endurance sports and including several Olympic champions, of blood- doping and connected insurance fraud. APA said 16 Austrian and 15 foreign athletes, 10 of them German, had been named in the letter while in its Thursday edition, the Tiroler Tageszeitung said that doctors were also involved. "Three doctors systematically conducted blood-doping over the past three years and are continuing until today," the paper quoted the letter, adding that doping incidents also took place in the time between 2000 and 2006. The anonymous letter lists names, locations and describes doping procedures, Tiroler Tageszeitung wrote, adding that the costs for the doping activities were charged to the athletes' insurance under guise of different medical treatments, thereby adding insurance fraud to the doping offence. The country's sports scene is still struggling from the fallout of the 2006 Turin Olympics doping scandal involving Austrian athletes. Only a few weeks ago, new accusations were levelled against athletes and a Vienna blood bank, which however remain unproven to date. It remains unclear if the most recent developments are in connection with this case or constitute a separate incident.