U.N. Secretary-General Ban Ki-moon said he could not determine whether the Israelis or Palestinians had conducted credible investigations into allegations of war crimes during last year's Gaza conflict as required under a U.N. resolution.

In a highly anticipated report released Thursday night to the 192-nation General Assembly, Ban said "no determination can be made on the implementation of the resolution by the parties concerned."

A U.N. panel, overseen by a respected South African jurist, Richard Goldstone, found evidence in September that both Israel and Palestinian militants may have committed war crimes during the fighting, in which 13 Israelis and almost 1,400 Palestinians were killed, including many civilians.

In November, the General Assembly endorsed the Goldstone report, urging Israel and the Palestinians to investigate alleged war crimes in Gaza or face the possibility of Security Council action if they didn't, under an Arab-drafted resolution.

Any action by the Security Council, however, is unlikely because the U.S. hold veto power as one of the five permanent members of the 15-nation body.

Israel said it has launched investigations into 150 separate incidents, including 36 criminal probes, and has gathered evidence from almost 100 Palestinians complainants or witnesses.

The Palestinians only created a commission to carry out an investigation in late January.

Ban only wrote a brief preface to the 72-page "report" which is largely composed of Israel's 58-page response, a Palestinian letter saying they're creating the commission and a brief letter from Switzerland in its role as depository of the Geneva Conventions.

On Friday, Israel's Foreign Ministry issued a response to the Secretary-General's report.

"Israel expresses satisfaction with the fact that the U.N. Secretary-General accurately reflected the document Israel submitted this week. This Israeli document gives full expression to Israel's commitment to carry out independent and trustworthy investigations that meet the standards of international law," the statement read.

Israel said its forces did everything it could to limit civilian casualties, but some human rights groups have voiced skepticism and said the Israeli military cannot be trusted to investigate itself.

Israel said the military operation against Gaza was launched in self-defense to protect civilians in southern Israel from rocket and mortar attacks from Gaza, which is under the control of the militant Islamic Hamas group.

Hamas leaders said they did not target civilians while firing hundreds of rockets at Israeli towns, and that the rockets fired from Gaza were meant to hit military targets but hit civilians by mistake because they are unguided.