Schleck, who has proclaimed his innocence, said in a statement he would continue his fight to discover how the diuretic got into his system.
After witnessing the analysis at the laboratory in Chatenay-Malabry, France, Schleck said: "The result of the counter test was positive but for me nothing changes: I just know that I did nothing wrong!
"I will therefore continue my search to find out how the substance could have entered my body.
"At the moment we are analysing minute by minute what exactly I have been doing, eating, drinking on the days before the control and on July 14 itself, who I met, what materials I came in contact with, what nutritional supplements I took."
Because Xipamide falls into a special category of substances under the World Anti Doping Code called 'Specified Substances', Schleck has a chance to prove his innocence.
The Code states that when an "athlete can establish that the use of such a specified substance was not intended to enhance sport performance, the period of ineligibility... shall be replaced with the following."
For a first violation athletes face anything from a reprimand or, at most, a one year's ineligibility.
A second violation would incur "two years ineligibility", in other words a two-year ban, while a third violation would incur a "lifetime ban".
-AAP