Italian cyclist Danilo Di Luca is optimistic about clearing his name after testing positive for the banned blood booster CERA during May's Giro d'Italia, he said on Wednesday.

The 2007 Giro champion, the runner-up in this year's race, was provisionally suspended in July when the results of the positive test were released by a Paris laboratory. Those results were confirmed by tests on the B samples this month.

"I cannot find an explanation for these two positive tests," he told reporters after a hearing with Italian Olympic Committee anti-doping prosecutors. "I'm convinced I'll come out of this clean."

Di Luca, who had previously indicated he would quit if the B samples were also positive, has said there could have been an unintentional mix-up with his tests.

The rider risks a ban of up to four years.

He served a three-month suspension in late 2007 after CONI found him guilty of frequenting a doctor accused of supplying doping products to athletes.

Last year CONI tried to ban him for two years for having abnormal hormone levels during the 2007 Giro but he was cleared after much legal wrangling.