LAUSANNE, Switzerland (AP) – American cyclist Tyler Hamilton appealed his two-year doping suspension to the Court of Arbitration for Sport on Wednesday.

The Olympic gold medalist asked CAS to overturn the April 18 decision by the independent American Arbitration Association to suspend him for a blood doping violation.

CAS usually issues verdicts within four months of an appeal.

Hamilton has consistently denied any doping violation and criticized the testing method used by the Union Cycliste International, cycling’s international governing body. He announced in April that he would appeal to CAS.

His is the first case based on a test designed to detect the presence of someone else’s red blood cells. A blood transfusion can increase endurance by providing extra oxygen-carrying red blood cells.

Hamilton tested positive on Sept. 11 during the Spanish Vuelta, a month after he won the time trial gold medal at the Athens Olympics. Hamilton’s initial blood sample in Athens tested positive, but that case was dropped because his backup specimen was mistakenly frozen and couldn’t be analyzed.

The Russian Olympic Committee has filed an appeal seeking to strip Hamilton of his gold medal and give it to silver medalist Vyacheslav Ekimov.

Hamilton, considered a possible successor to six-time Tour de France winner Lance Armstrong, was fired by the Swiss-based Phonak team in November. He is eligible to return to competition in April 2007.