Israeli forces today pressed on with a deadly ground, sea and air assaults against Hamas militants in the Gaza Strip that has cut the territory in two and France spearheaded diplomatic efforts to obtain a truce.

A Hamas official said a delegation of the Islamist group would head for talks in Egypt, which has also launched contacts to achieve a ceasefire to end Israel's 10-day-old offensive.

Explosions from gunfire rocked Gaza overnight after Israeli soldiers moved into a northern zone and asked residents to leave their homes to avoid being hurt in the fighting. Some families sought refuge in nearby United Nations run schools.

Israeli aircraft bombed more than 30 targets overnight, including several homes of Hamas members used as weapons depots, tunnels and a suspected anti-aircraft rocket launcher, a military spokesman said. There were no reported casualties.

Israeli media said Israeli troops were searching house-to-house in parts of Gaza for Hamas suspects. Israel Radio reported gun battles between Israeli and Hamas militants in the streets of Gaza City, and said Israeli troops thwarted an attempt to capture one of them in a fight inside a house.

UN Secretary-General Ban Ki-moon said he had recalled his special Mideast envoy for briefings, adding he was worried about the humanitarian situation in Gaza.

Israel launched its offensive with aerial bombardments on December 27 to curtail Palestinian rocket attacks from Gaza ahead of an Israeli national election next month, then expanded it into a ground invasion on Saturday.

At least 512 Palestinians have been killed at least a quarter of them civilians, a UN agency said. Forty-two, mostly civilians were killed yesterday, a medical source said.

Four Israelis have been killed by rockets and mortars fired at Israel since the offensive began, and an Israeli soldier was killed in fighting yesterday and 48 were wounded after Israel expanded its operation into a ground invasion.

Israel's advances into Gaza have carved the 40-kilometre long coastal territory into two separate zones, and forces have surrounded its largest urban area of Gaza City.

French President Nicolas Sarkozy was expected to arrive in the region today in a fresh diplomatic push for a truce, which Israel has thus far resisted.

Hamas was sending representatives to Egypt for talks for the first time since the fighting began, said Hamas' Ayman Taha.

The United States, the region's powerbroker and Israel's closest ally, looked all but sidelined by the pending handover of its presidency, offering Europe a chance to take the lead and press for an end to the Israeli assault.

US President-elect Barack Obama has been silent on the crisis, his advisers saying only President Bush would speak for Washington until Obama is sworn into office on January. 20.

The Bush administration has supported Israel, saying Hamas had to halt rocket fire at Israel for a truce to take shape.

Sarkozy, who meets Israeli leaders on Monday, has not let the end of France's European Union presidency last week prevent him from taking a vanguard role, but will share the work with a separate delegation led by the Czech foreign minister.

Before heading to Egypt for talks before meetings in Israel and the Palestinian territories, Sarkozy said he "condemned this offensive" for distancing chances for peace and making it harder to get aid to Palestinians in Gaza.

Aid groups have warned of a dire humanitarian situation in Gaza, where water, food and medical supplies were running short.

A foreign Red Crescent doctor said on Sunday: "Civilians are being killed ... shells are severing people's legs, shrapnel is going into people's bodies and into people's homes, a lot of people are being cut down. Everyone is terrified."

Israeli Prime Minister Ehud Olmert assured Sarkozy in a telephone call yesterday that aid for the 1.5 million people trapped in the Gaza Strip would continue.

Israel said about 80 trucks with humanitarian supplies would be sent to Gaza, in addition to some fuel, and several busloads of foreigners would be permitted to leave Gaza today.

But Israel's president Shimon Peres made clear there would be no military let-up until Hamas stopped firing.

"We shall not accept the idea that Hamas will continue to fire and we shall declare a ceasefire. It does not make any sense," Peres, the largely titular head of state, said.

Israel has said that the Gaza operation, though sparking waves of protests around the world, could last many days.

Government officials said Israel had set several goals, including weakening Hamas by killing its fighters and destroying its rocket arsenal.

In addition Israel hopes to deter cross-border salvoes and win international backing for new security arrangements along the Egyptian-Gaza border to prevent Hamas from rearming through tunnels, which have been bombed in the current campaign.

Iranian-backed Hamas is estimated to have about 25,000 fighters. Israel has not disclosed how many troops are involved in the operation but thousands of reservists were on stand-by.

Hamas called off a six-month truce last month and stepped up its rocket attacks, citing Israeli raids and a continuing blockade of the enclave Israel quit in 2005.

International peace efforts aimed at creating an independent Palestinian state foundered after Hamas won elections in 2006 and drove Fatah forces loyal to Palestinian President Mahmoud Abbas from Gaza a year later.

Hamas has insisted it would not be subdued. "The Zionist enemy must know his battle in Gaza is a losing one," Abu Ubaida, a spokesman for Hamas's armed wing said yesterday.

Ali Larijani, speaker for the parliament in Iran, a backer of Hamas, said "the Zionists should know that Gaza will become their graveyard."

Heavy civilian casualties in the territory packed with 1.5 million people could increase world pressure on Israel to halt its biggest military operation in Gaza in four decades.

The fighting also holds political risks for Israeli leaders ahead of next month's election, if its forces take heavy casualties in the ground fighting. Schools and malls have been shut for days in southern Israel, and streets were eerily empty.