The United Nations sharply criticized Israel for using live ammunition in May against Palestinian protesters who tried to scale an Israeli security fence on the Lebanese border, according to a U.N. report reviewed by The Wall Street Journal.

The confidential report to the U.N. Security Council, dated Friday, also accuses Israel of violating the 2006 cease-fire agreement that ended the six-week conflict between Israel and Hezbollah, the Lebanese Shiite group. The May 15 incident near Maroun al-Ras, Lebanon, led to seven deaths and 111 injuries.

The report also accuses about 1,000 protesters of a group of 10,000 that day of violating the cease-fire by carrying out a "provocative and violent act."

The report appears to have further strained relations between the U.N. and Israel and is likely to increase Israel's isolation amid an international campaign to challenge its policies on the occupied territories.

The U.N. blamed Israel for turning too quickly to live ammunition to stop the protesters advancing on the Israeli border. "Other than firing initial warning shots, the Israel Defense Forces did not use conventional crowd-control methods or any other method than lethal weapons against the demonstrators," the report said. It added that the act "constituted a violation of [the cease-fire] resolution and was not commensurate to the threat to Israeli soldiers."