UNITED NATIONS — 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. holds veto power as one of the five permanent members of the 15-nation body.

Israel says 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.