German cycling team Telekom have confirmed that their rider Jan Ullrich has failed an out-of-competition drug test.
The former Tour de France champion tested positive for a controlled substance during his spell in a clinic where he was recovering from a knee injury.
Telekom are investigating German Ullrich's failure and team spokesman Olaf Ludwig admitted they were currently in the dark.
He said: "At the moment, only the information is with us. Nothing else."
Ullrich, who won the 1997 Tour de France, had already announced that his knee injury would keep him out of this year's race, due to start on Saturday.
The 28-year-old has had a bad year and last month he was convicted of drink-driving.
The result will not be confirmed until a second sample, taken at the same time as the first, is also tested.
However, the German team hinted that they will take no action against the rider as he was not in a condition to compete professionally.
The surprise test was carried out on behalf of Telekom at the Bad Wiesse clinic where Ullrich was recuperating following an operation on May 20th.
Ludwig said: "The problems with his knee permitted neither training nor competition, so any intention of manipulating performance can be clearly excluded."
PA