Russian Alexandr Kolobnev said Tuesday he had nothing to hide shortly after becoming the first rider to leave this year\'s Tour de France in disgrace. Kolobnev was forced out of the July 2-24 event after cycling\'s governing body, the UCI, announced that a urine sample taken from the Katusha rider in-race on July 6, had tested positive for hydrochlorothiazide, a diuretic. In a statement, Kolobnev said: \"Yesterday (Monday), during the rest day I was informed the laboratories had found a substance, hydrochlorothiazide, which I do not know where it\'s come from. \"While I await more information, I have nothing to say about it for respect to the race organisers and cycling in general.\" Kolobnev was questioned for several hours by police before returning to his hotel in nearby Vezac. \"After a police investigation nothing suspicious was found so we are waiting for the results and what the investigation may say,\" he added. \"Asked by my team about what I wanted to do after this news, I have decided voluntarily leave the Tour de France while waiting for the B-sample in the following days, again showing my respect to UCI and WADA rules. \"I must say that I have received all the support from the team from the beginning and I have not been fired, as some media reported yesterday.\" Katusha, in a bid to save the Tour and the team from further controversy, said late on Monday\'s rest day that Kolobnev would not continue. And they warned he would be sacked and faced a substantial financial penalty if the B sample was also positive. \"Team Katusha rider Alexandr Kolobnev, after testing positive for a diuretic at a medical examination during the Tour de France’s first week, decided to suspend himself according to UCI rules, waiting for the B-sample,\" said Katusha\'s statement. \"At the moment, team management and the rider have no further comment. It has to be noticed that internal rules in Team Katusha say that the rider, if the B-sample also tests positive, will be fired and will have to pay five times his salary as a fine.\" A diuretic, hydrochlorothiazide is listed as a banned substance because it can also be used to mask other drugs.