Geneva - Israel's recent military operation in the Gaza Strip was illegal and included violations of human rights and possible crimes against humanity, the United Nations expert on the Palestinian territories said Monday.

"To the extent that the combat zone was so densely populated by civilians, it meant that, with the types of weaponry relied upon, there was no lawful way to carry out the Israeli military operations," said Richard Falk, addressing the Human Rights Council in Geneva.

The UN special rapporteur said the death ratio of 1,434 Palestinians to 13 Israelis was "a basis for challenging the legality" of the operation against an "essentially defenseless society."

Speaking to reporters later, Falk insisted that Israel had diplomatic alternatives to engaging in an armed conflict, specifically, proposals by the Islamic Palestinian movement Hamas that controls the Gaza Strip for a ceasefire with Israel.

"These initiatives, completely ignored by Israel, gave Israel a diplomatic alternative," said Falk, who called the offensive "an intrinsically unlawful recourse to force."

Falk also focused on what he said was Israel's effective denial of Palestinians' right to to flee the combat zone.

"Such a war policy should be treated as a distinct and new crime against humanity," Falk said.

Falk reiterated calls by other UN officials for an investigation into war crimes allegations regarding acts by Israel and Hamas.

He issued a similar call in a report released last week and said that if an 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."

Falk admitted that the UN Security Council was unlikely to approve such a mechanism, saying the United States would probably wield its veto power in such a scenario.

Israeli military chief of staff Gaby Ashkenazi on Monday said Israeli soldiers did not systematically and wilfully kill Palestinian civilians "in cold blood." He noted there were ongoing investigations and if "single cases" emerged, these would be brought to justice.

Testimonies of Israeli soldiers published by Israeli newspapers in recent days, paint 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.

Alongside Falk, Olivier de Schutter, the special rapporteur on the right to food, delivered a joint report of nine UN experts, which also condemned the military operation and Israel's ongoing blockade on the coastal territory.

De Schutter also said the experts were concerned by the use of human shields by both parties, allegations that Hamas executed Palestinian civilians during the Israeli operation and "questionable use" of certain weapons during the fighting.

Both experts also called Palestinian rocket fire against Israeli civilians unlawful.

Aharon Leshno-Yaar, Israel's ambassador to the UN in Geneva, said the joint report "downplays terrorists threats we face" and noted a recent attempt to blow up a car bomb near a shopping mall in northern Israel.

He said there was an established double-standard against Israel.

Israel, he said, tried to ensure that its operations were "conducted in accordance with the requirements of international humanitarian law."

Falk, a controversial Jewish-American jurist, has been deemed by Israel to be "unwelcome" and was denied entry to the country last year, an incident he called an "unfortunate precedent." (dpa)