On Tuesday morning Tyler Hamilton's Phonak team admitted that their star rider has returned positivePhonak manager Urs Freuler told procycling this morning that his team will hold a press conference in Zurich at 6pm this evening to comment on "irregularities" in a blood sample supplied by Tyler Hamilton. According to comments by Phonak press chief Georges Luedinger to Associated Press, Hamilton's A-sample from tests after both his Olympic time trial win victory and a stage of the current Vuelta a Espana showed evidence of "mixed red blood cells, apparently evidence of a blood transfusion." Leudinger added that Hamilton denied using transfusions to enhance his performance. "Tyler has told us that he hasn't done anything," he told AP. Phonak's directeur sportif at the Vuelta, Alvaro Pino, adopted the same line: "He has maintained his innocence," said Pino on Tuesday morning. "He said that, whatever the team decides, he will do everything in his power to defend himself against the accusations. "He told me, 'Be calm, because this will work out in my favour. I'm telling you that sincerely, because there's absolutely nothing in this'," Pino added. Hamilton quit the Vuelta last Friday complaining of stomach problems. Earlier Freuler had confirmed rumours already reported in Spain and Italy this morning: "There is something strange with a test from Tyler and we will comment on it this evening," he told procycling. "It is to do with his blood parameters. We will continue to collect information throughout the day. This blood test was implemented for the first time at Athens: it's a strange case." Phonak were apparently alerted to complications with Hamilton's blood test when UCI officials contacted team doctor I¤aqui Arratibel. La Gazzetta dello Sport reports that Hamilton has already asked his legal team to organise his defence. It is believed that his defence is based on the claim that anomalies in his blood are the result of a recent operation. Freuler said this morning that Phonak preferred to comment on the affair before the UCI announces the results of Hamilton's counter-analysis. "Tyler wants to be the first to comment on this," Freuler stated. No rider, or indeed sportsman in any discipline, has ever been convicted of doping on the basis of a blood sample. Until the recent introduction of a new, reinforced anti-doping protocol by the UCI at the Tour de France, the scope of blood tests was restricted to the health check-ups introduced by the UCI in 1997.