German cycling team T-Mobile has been rocked by a new doping scandal after Italian rider Lorenzo Bernucci was sacked on Tuesday for failing a drugs test.

Bernucci, 27, tested positive for the banned appetite suppressant Sibutramine on August 15 during the Tour of Germany.

"We do not know if this was an attempt at performance enhancement or just poor judgment," said team general manager Bob Stapleton.

"But we know it is unacceptable that riders take any medication without the approval of the team doctor. It's a clear violation of our code of conduct and we have acted on that basis."

Following the sacking of Patrik Sinkewitz during the Tour de France, when abnormally high levels of testosterone were found in his blood, this is another blow for the German team.

T-Mobile announced on August 9 it would continue its sponsorship until 2010, but warned that any further doping violations by the team's riders could damage the agreement.

Bernucci, who lives in Monaco, was withdrawn from the Vuelta a España after Monday's third stage. It is up to the Monaco cycling federation to investigate who will be responsible for further investigating the incident and for determining additional sanctions.

After learning of his positive test, Bernucci told the team management he had taken the drug, purchased over the counter at a chemist's in Italy, in order to suppress his appetite.

He reportedly used the product for four years but did not know it was added to the World Anti-Doping Agency (WADA) list of prohibited substances last year.

According to UCI rules a first violation for using Sibutramine, if proven to not have been used to enhance sporting performance, can result in a warning or the maximum penalty of a one-year suspension.