A veteran UN war crimes investigator acknowledged his probe of possible war crimes by Israel and Hamas - which included interviewing dozens of victims and poring through the files of human rights groups - is unlikely to lead to prosecutions.

Israel has refused to cooperate, depriving his team access to military sources and victims of Hamas rockets. And Hamas security often accompanied his team during their five-day trip to Gaza last week, raising questions about the ability of witnesses to freely describe the group's actions.

But the chief barrier remains the lack of a court with jurisdiction to hear any resulting cases stemming from the investigation into Israel's three-week offensive in Gaza which ended in January and was designed to stop years of Hamas rocket fire into southern Israel.

"From a practical political point of view, I wish I could be optimistic," Judge Richard Goldstone said, citing the legal and political barriers to war crimes trials.

Still, Goldstone hopes his group's report - due in September - will spur action by other UN bodies and foreign governments.

Goldstone, a South African judge who prosecuted war crimes in the former Yugoslavia and Rwanda, refused to comment on the investigation's content. But AP interviews with more than a dozen Gazans who spoke to the team reveal a wide-ranging investigation into the war's most prominent allegations.