Sochi: The first doping cases to hit the 2014 Sochi Games emerged Friday after a double gold-medal winning German female biathlete and an Italian bobsledder tested positive for banned substances.
German biathlete Evi Sachenbacher-Stehle, who has won two gold medals at previous Olympic Games, confirmed she had tested positive, describing it as the "worst nightmare you can imagine".
Meanwhile, the Italian Olympic Committee said Italian bobsledder William Frullani had tested positive for a banned substance and had already been kicked out of the Sochi Games.
The news that a well known athlete as Sachenbacher-Stehle has failed a doping test has caused shock waves in Germany, which for years has prided itself on its tough anti-doping fight.
"I cannot explain how this positive doping test came about," Sachenbacher-Stehle said in a statement, adding that she had had all her dietary supplements tested in a laboratory.
Reports said that the positive test -- carried out on February 17 -- may have come about due to contamination from imported energy bars.
"I am living through the worst nightmare that you can imagine," she added.
"I can only assure everyone that I have never knowingly taken a banned substance and will do everything to clear this up so there are no questions," she added.
Frullani, 34, tested positive on February 18 for the banned substance dymetylpentylamine. He has been replaced in the Italian four-man bobsleigh team by Samuele Romanini.
The German Olympic Sports Confederation (DOSB) said in a statement that both Sachenbacher-Stehle`s `A` and `B` samples had tested positive for the stimulant methylhexanamin.
It said she appeared before an IOC disciplinary commission, has now been excluded from the German team and was leaving Sochi immediately.
"Every doping case is a great disappointment. But it is also proof that the control system works," said Germany`s chef-de-mission Michael Vesper.
Sachenbacher-Stehle, 33, spent most of her long career as a cross country skier before switching last season to biathlon, which mixes both cross country skiing and shooting.
It was as a cross country skier that she won gold in the 4x5 km relay in the Salt Lake City Games of 2002 and then gold in the team sprint in Vancouver 2010.
Sachenbacher-Stehle already hit controversy at the Turin Olympics of 2006 when she and several other athletes were given a five-day ban from competition due to excessive levels of haemogloblin.
She argued that the finding was due to a genetic condition and not due to doping.
At Sochi, her best results were fourth place in the women`s mass start and also fourth place in the mixed relay.
She had announced Thursday that she had not been included in the women`s biathlon relay Friday.
"It is sad for all of us and a shock," the head coach of Germany`s national cross country team Frank Ullrich told AFP`s German sports subsidiary SID.
Her brother Josef told the mass-circulation daily Bild: "She has nothing to reproach herself for. She despises this (doping) and would never dope."
The last Winter Olympics in Vancouver 2010 produced only one positive doping test in the course of the Games.
Olympics chiefs believe they are winning in the fight against doping, after the Salt Lake City Games of 2002 and the Turin Games of 2006 produced seven positive tests apiece.
The IOC, which oversees drug testing at the Olympic Games, is carrying out almost 2,500 drug tests at Sochi 2014 with an extra emphasis on out-of-competition tests.
IOC medical commission chairman Arne Ljungqvist earlier in the Games warned athletes that a new 10-year period of storing samples and increasingly sophisticated methods meant there was nowhere for cheats to hide.
"The message to athletes is that if you cheat and if we don`t find you now, we may find you later. But we will certainly find you sooner or later," he said.