GAZA CITY, Gaza Strip - Israel, under international pressure, is considering a 48-hour halt to its punishing four-day air campaign on Hamas targets in Gaza to see if Palestinian militants will stop their rocket attacks on southern Israel, Israeli officials said yesterday.

Any offer would be coupled with a threat to send in ground troops if the rocket fire continues.

Prime Minister Ehud Olmert discussed the proposal - floated by France's foreign minister - and other possible next steps with his foreign and defense ministers, Israeli officials said, speaking on condition of anonymity.

President Bush and Secretary of State Condoleezza Rice called leaders in the Middle East to press for a durable solution beyond any immediate truce.

And members of the Quartet of world powers trying to promote Mideast peace concluded a conference call with an appeal for an immediate cease-fire. The Quartet powers are the United States, the United Nations, the European Union and Russia.

The European Union itself late yesterday also urged an immediate truce and for Israel to reopen borders to allow vital supplies to reach Gazans. The Paris statement by the 27-member bloc avoided blaming either side for the current fighting.

In its meeting last night, Israel's leadership trio stepped up preparations for a ground offensive, conducting a telephone survey among Cabinet ministers on a plan to call up an additional 2,500 reserve soldiers, if required. Earlier this week, the Cabinet authorized a callup of 6,700 soldiers.

After the four-hour meeting, Olmert's office issued a statement early today (Israel is 7 hours ahead of Philadelphia), saying no details of the discussion would be made public.

But Israeli officials, speaking on condition of anonymity, said the leaders wanted Hamas to agree to stop the rocket fire before Israel considers a truce.

And even amid talk of a truce, Israeli warplanes continued to unload bombs on targets in Gaza. Powerful airstrikes caused Gaza City's high-rise apartment buildings to sway and showered streets with broken glass and pulverized concrete. Israel's ground forces on Gaza's border also used artillery for the first time.

Hamas kept up its rocket barrages, which have killed four Israelis since the weekend, and sent many more in running for bomb shelters - some of them in cities under threat of attack for the first time, as the range of the rockets grows. *