Geneva  - The recent Israeli offensive in the Gaza Strip lacked a legal basis and potentially amounted to a "crime against peace," according to a United Nations expert report available on the internet Friday.

Israel did not exhaust the diplomatic options available to it before engaging in the conflict, Richard Falk, the UN Special Rapporteur for human rights in the Palestinian territories, wrote in the report.

Falk said there was reason to suspect that Israel failed to distinguish between civilian and military targets. He also said the Israeli military intentionally used disproportionate amounts of force and did not allow potential refugees to escape the conflict zone.

This made "the attacks impossible to reconcile with international law," Falk said, blaming Israel for the breakdown of a ceasefire with the Palestinian Hamas movement that rules the Gaza Strip in the lead- up to the offensive.

Falk recommended the establishment of an "expert enquiry" to conclude if war crimes or other illegal acts were committed by parties to the fighting, including Israel and Hamas.

If the enquiry found that individuals could be criminally responsible, a next step would be the setting up of a UN-sponsored "ad hoc criminal tribunal for occupied Gaza."

Israel's claim that it was acting out of right to self defence, Falk wrote, should also be examined as it is an occupying power in Gaza.

The report was posted to a UN website ahead of a discussion on human rights in the Palestinian territories set to take place Monday at the Human Rights Council in Geneva.

On Friday, the council adopted Israel's periodic rights review, one each UN member is to undergo every four years as part of a new system introduced two years ago.

Israeli media published Friday accounts of soldiers who served in Gaza, which painted a picture of lax rules of engagement that allowed for the killing of Palestinian civilians during Israel's 22-day offensive in the Gaza Strip. The country's Ministry of Defence has launched a probe.

Falk, who has the mandate to review all human rights issues in the West Bank and Gaza Strip, focused his report solely on the last offensive, during which 1,434 people were killed, according to his statistics.

Palestinian rights group say a third of those killed were civilians.

The report was not based on his own on-the-ground investigation, Falk said, as he was denied access to Israel.

In December, Falk was considered "unwelcome in Israel," according to the Foreign Ministry. He was detained at a Tel Aviv airport and deported. (dpa)