Defense officials said the troops could be ready for action by Friday. They spoke on condition of anonymity because the army's preparations are classified.

Osama Hamdan, a Hamas representative in Lebanon close to the group's leadership in Syria, told Al-Jazeera television that Hamas will reject any initiative that does not include the withdrawal of the Israeli army from Gaza and the opening of all of the territory's border crossings.

"Any proposal that does not include these bases is unacceptable and no one should bother by presenting such proposals," he said.

"The idea of an international force is rejected and such forces which will come to Gaza to protect Israel will be dealt with as enemy forces," he said.

Israel carried out 40 airstrikes in Gaza on Wednesday, the army said. An Israeli combat officer, identified as Lt. Col. Amir, said troops neutralized hundreds of explosives devices, including booby-trapped houses, and discovered many tunnels dug by militants.

Despite the army's push, Gaza militants fired 14 rockets Wednesday, including hits on the towns of Beersheba and Ashkelon.

Rocket fire has fallen off somewhat as Israeli troops tighten their hold on Gaza, taking over open areas used to launch rockets, but Gaza residents say militants are still launching from heavily populated areas.