"My message to the international community is that our silence and complicity, especially on the situation in Gaza, shames us all," Tutu said Thursday. "It is almost like the behavior of the military junta in Burma."

He told a news conference in Gaza he was shocked by the conditions in the area, describing the narrow coastal strip as "desolate and scary" because of the severe shortages of fuel and other basic goods, saying there was no justification for the deteriorating humanitarian situation there.

Tutu, the former archbishop of Cape Town, was in Gaza heading a U.N. probe into the November 2006 Israeli shelling of two homes in Beit Hanoun in the northern Gaza Strip, which killed 19 civilians from the same family, including five women and eight children.

While he is due to report his findings to the U.N. Human Rights Council session in Geneva in September, the envoy on Thursday condemned the incident as a "massacre," after speaking to the survivors and victims' relatives.

"We are at the stage of shock by what we subsequently heard from the survivors of the November Beit Hanoun massacre," he said.

Tutu added that the mission would make recommendations "to protect Palestinian civilians from further Israeli assaults."

The South African cleric said that Israel's claim that a technical fault caused the shells to hit the two houses, in a border area where militants fire rockets at southern Israel, "fell short of accountability."

The Israeli army decided in February that no charges would be brought against Israeli soldiers involved in the attack.

In a June 2007 report, the U.N. mission said that "whether the casualties at Beit Hanoun were caused by mistake, recklessness, criminal negligence or were willful, those responsible must be held accountable."

Israel has refused to cooperate with the mission on the grounds that it was biased. It has also refused the committee entry to the nearby Israeli town of Sderot, a favorite target for Palestinian home-made rockets.

During a meeting with deposed Hamas Prime Minister Ismail Haniyeh on Wednesday, Tutu said he called for stopping rocket fire into Israel, telling him that targeting civilians in Sderot was also a "gross violation of human rights."

Tutu was awarded the Nobel peace prize in 1985 for his prominent non-violent struggle against apartheid in South Africa, and has called for the two warring sides to negotiate.

"That was our experience in South Africa," he said on Wednesday. "Peace came when former enemies sat down to talk."

Hamas has been controlling the impoverished strip since it overthrew the Fatah-led Palestinian Authority last June, but has been engaged with Israel in indirect truce talks through Egyptian mediation, which have made little headway.

Hamas officials on Thursday blamed Israel for refusing to accept the Egyptian-brokered conditions for a ceasefire after the Islamist group had accepted stopping rocket fire in return for reopening of the crossings.

Israel, backed by the West, imposed stiff sanctions on Gaza after Hamas won the January 2006 elections and demanded the group recognize Israel, give up violence and endorse previous Palestinian agreements with Israel – something that has not happened yet.

The blockade was further tightened after Hamas' seizure of the area 11 months ago, with only minimum essentials entering into Gaza, where 70 percent of the 1.5 million residents, most of them refugees from 1948, live on U.N. food aid.

"What is happening in Gaza is unacceptable," Tutu said on Wednesday. "We have already seen and heard enough to move us to tears."

The Israeli Ha'aretz daily quoted the U.N. envoy as saying he "expects the Israelis, as those who remember the Holocaust, like the South Africans, to be sensitive to the suffering of the Palestinians."

Some Israeli commentators are becoming more critical of the policy isolating Hamas, which Israel and the U.S.-led West regards as a terrorist group, and are seeking a ceasefire that will stop the militant rocket fire, the Israeli military attacks and lift the blockade on Gaza.

Meanwhile, in what Palestinians believe might be linked to the U.N. mission, Israeli troops early Thursday raided Beit Hanoun and arrested 60 people in a military incursion.

Palestinians in the town said troops used loudspeakers to order residents aged 16 to 60 to gather in a square and took away dozens as they pulled out. Armored military bulldozers also destroyed some farmland in the process.

Israeli military spokesmen confirmed the incursion as a "routine activity" and captured 60 "wanted Palestinians" to be interrogated.