Israel's deadly shelling in the Gaza Strip in November 2006 may constitute a war crime, South Africa's Archbishop Desmond Tutu said in a report to the United Nations released on Monday.

Tutu, who serves as an independent UN human rights envoy, said Israel must be held accountable for its strike that hit two homes in the Gaza town of Beit Hanoun, killing 18 people.

"In the absence of a well-founded explanation from the Israeli military - who is in sole possession of the relevant facts - the mission must conclude that there is a possibility that the shelling of Beit Hanoun constituted a war crime," he said in the report to the UN Human Rights Council.

The South African cleric said his mission had also made clear to the Palestinian faction Hamas that "the firing of rockets on the civilian population in Israel must stop".

Israeli foreign ministry spokesman, Yigal Palmor, said Tutu never approached Israeli authorities to seek their analysis of the facts. "It's regrettable to hear that a person with a renowned name like Desmond Tutu says such things without having investigated the facts, rather from press reports," he said.

The Israeli military, after conducting its own investigation, said in February that it had directed artillery fire against the Beit Hanoun area on November 8, 2006 on the basis of intelligence that militants were planning rocket attacks.

It said that "the injury of the Palestinian civilians was not intentional and was directly due to a rare and severe failure in the artillery fire control system".

No action was taken against military personnel because they bore no legal blame for the incident, it added.

Request denied

Tutu, awarded the Nobel Peace Prize in 1985 for his nonviolent struggle against apartheid in South Africa, visited Gaza in May via Egypt. He said three requests to travel via Israel and interview Israeli officials and those living near the border with the occupied Palestinian territory were refused.

This was itself "an obstacle to the balance that Israel seeks".

Tutu said there should be an "independent, impartial and transparent investigation" of the shelling of Beit Hanoun, a town of 35,000 of whom some 70 per cent are registered refugees.

"Regardless of whether the casualties at Beit Hanoun were caused by a mistake, recklessness, criminal negligence or wilful conduct, those responsible must be held accountable," he said.

Israel and the West tightened restrictions last year on the Gaza Strip, attempting to isolate Hamas, after the group's fighters seized the territory. The Islamist group opposes Palestinian President Mahmoud Abbas' peace talks with Israel.

Israel and Hamas entered an Egyptian-brokered truce in June.