Devastation in the Gaza Strip as Israeli forces gather on boundary
Israel's air assault on Gaza is "the first in several stages" of operations aimed at ending militant rocket fire, Prime Minister Ehud Olmert has said.
As bombing continued for a fourth day, another top official said Israel was ready for "long weeks of action".
Palestinian officials say more than 360 people have been killed since Saturday. Four Israelis have died in rocket fire.
As EU officials met to discuss the crisis, some reports from Israel said it was considering a temporary truce.
Mr Olmert was set to discuss the idea of a 48-hour suspension, suggested by France, with his officials later in the day, the French news agency AFP said.
But Infrastructure Minister Benjamin Ben-Eliezer warned a truce would allow militant group Hamas - which controls Gaza - "to regain strength... and prepare an even stronger attack against Israel".
US President Bush agreed in a telephone conversation with Palestinian President Mahmoud Abbas that for any ceasefire to be effective it had to respected by Hamas, the White House said.
A BBC reporter says Israeli tanks and troops are massed along Gaza's border.
Correspondents say this could be a prelude to ground operations, but could also be intended to build pressure on Hamas.
European Union foreign policy chief Javier Solana called for an immediate ceasefire and the opening of crossings to allow humanitarian aid into Gaza, as EU foreign ministers held talks in Paris to discuss the crisis.
Foreign ministers from the Quartet trying to broker peace in the Middle East - the US, Russia, the UN and the EU - also held a conference call, no details of which were released.
On Tuesday, Israeli jets attacked more targets linked to Hamas, hitting a number of government buildings and security installations.
The UN has called for an investigation into the attacks, which are causing heavy civilian casualties. It says at least 62 of the Palestinians killed so far were women and children.
Richard Falk - the UN special rapporteur for human rights in the Palestinian territories - said the international community must put more pressure on Israel to end its assault.
"Israel is committing a shocking series of atrocities by using modern weaponry against a defenceless population - attacking a population that has been enduring a severe blockade for many months," Mr Falk said in a BBC interview.
But Israeli officials said there was more to come.
The Israeli military "has made preparations for long weeks of action", deputy defence minister Matan Vilnai said.
Mr Olmert's statement that the bombardment was "the first of several stages approved by the security cabinet" was quoted from a briefing he gave to President Shimon Peres on Tuesday.
Separately, Israeli naval vessels confronted pro-Palestinian activists seeking to break the Gaza blockade by boat. The activists said one vessel rammed them; their boat made port in Lebanon with heavy damage on one side.
The Egyptian-Gaza border was due to be opened to permit more trucks carrying aid to enter the territory, and for wounded Palestinians to be transported to Egyptian hospitals.
Egyptian President Hosni Mubarak, under popular pressure to open the crossing fully, said that could not happen while Hamas, rather than the Palestinian Authority, led by its rival Fatah, controlled the border.
Demonstrators in Yemen, angered by Egypt's co-operation with the blockade on Gaza, briefly stormed the country's consulate in Aden, where they burned an Egyptian flag and hoisted a Palestinian one.
There have been angry protests against the Israeli offensive in many other cities across the Arab world and in several European capitals.
Binyamin Netanyahu: 'Terrorists cannot have immunity'
Hamas has pressed on with rocket and mortar assaults, killing three Israeli civilians and a soldier in areas that have not previously suffered such fatalities.
Israeli military officials said rocket attacks landing more than 25 miles (40km) from Gaza put nearly 10% of Israel's population of seven million within range.
Israeli political leaders have been under pressure to act against rocket fire with a general election looming in early February.
Opposition leader Binyamin Netanyahu has backed the offensive, telling the BBC that "Israel is using a fraction of its power to try to target surgically the terrorists".
The strikes began less than a week after the expiry of a six-month-long ceasefire deal with Hamas, which has controlled Gaza since 2007.
Correspondents say short of a full-scale invasion of Gaza, it is unlikely Israel will be able to prevent rocket fire permanently.
Israel dismantled its strategic settlements and military bases in Gaza in 2005 but has kept tight control over access in and out of the narrow coastal strip and its airspace.
GAZA VIOLENCE 27-30 DECEMBER
1. Ashdod: First attack so far north, Sunday. Woman killed in second rocket attack, Tuesday 2. Ashkelon: One man killed, several injured in rocket attack, Monday 3. Sderot: rocket attacks 4. Nevitot: One man killed, several injured in rocket attack, Saturday 5. Civilian family reported killed in attack on Yabna refugee camp, Sunday 6. Israeli warplanes strike tunnels under Gaza/Egypt border, Sunday 7. Three brothers reported killed in attack on Rafah, Sunday 8. Khan Younis: Four members of Islamic Jihad and a child reported killed, Sunday. Security officer killed in air strike on Hamas police station, Tuesday 9. Deir al-Balah: Palestinians injured, houses and buildings destroyed, Sunday 10. Tel al-Hawa - Interior ministry and Islamic University badly damaged, Monday. At least three buildings in ministry compound hit, Tuesday 11. Gaza City port: naval vessels targeted, Sunday 12. Shati refugee camp: Home of Hamas leader Ismail Haniya targeted, Monday 13. Intelligence building attacked, Sunday 14. Jebaliya refugee camp: several people killed in attack on mosque, Sunday 15. Beit Hanoun - two girls killed in air strike, Tuesday 16. Israeli soldier killed at unspecified military base near Nahal Oz border crossing - five other soldiers wounded in same rocket attack, Monday night.
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