Sixty members of the Palestinian Authority Chairman Mahmoud Abbas' security forces in Gaza should be court-martialed for their failure to prevent a Hamas takeover there last month, an official committee of inquiry concluded Thursday, according to an official in Abbas' office. The final report is to be made public Friday. Earlier Thursday, Mohammed Dahlan, a leader of Abbas' vanquished forces in Gaza, announced that he is resigning as national security adviser. Dahlan cited health reasons, but Palestinian government officials said Abbas asked him to step down because the committee of inquiry concluded Dahlan bore much of the responsibility for the humiliating defeat of the pro-Abbas forces by Hamas in mid-June. Dahlan's office denied he was asked to resign, and said he stepped down for medical reasons only. It was not clear whether Dahlan is among the 60 officers to face trial in a military court. The committee was headed by a senior Abbas aide, Tayeb Abdel Rahim. Investigators heard 120 hours of testimony, including from Dahlan and other senior security commanders. The official in Abbas' office said the investigation found flaws in the performance of Abbas' troops, but did not elaborate. He spoke on condition of anonymity because the report has not yet been published. Among the 60 facing trial in a military court are officers of various ranks, he said. Abbas has already dismissed or accepted the resignation of more than a dozen Gaza security officers.