Oct 7 (Reuters) - Nigerian sprinter Blessing Okagbare, who was provisionally banned after testing positive for human growth hormone before the Tokyo Olympics, has been hit with three separate anti-doping charges, the Athletics Integrity Unit (AIU) said on Thursday. Okagbare, who won silver in the long jump at Beijing 2008, had competed in the 100m heats in Tokyo on July 31 and was due to run in the semi-final before being suspended. The AIU said she tested positive on July 19 and on Thursday charged her with the presence and use of a prohibited substance following the detection of human growth hormone. It added that the second charge was in relation to recombinant erythropoietin (EPO) detected in her sample which was collected during an out-of-competition test on June 20 in Nigeria. "The AIU requested EPO analysis be conducted on the sample on July 29 and the adverse analytical finding was reported to it on Aug. 12," the AIU said in a statement, adding Okagbare was notified on Aug. 20. A further charge was issued over Okagbare"s "refusal to co-operate with the AIU"s investigation into her case." "Specifically, it is alleged that the athlete failed to comply with a formal requirement to produce relevant documents, records and electronic storage devices, which was issued to the athlete by the AIU on Sept. 15," the AIU added. The AIU said that Okagbare had denied all charges and requested that they be submitted to a hearing before a disciplinary tribunal.