Israel's army said on Tuesday it had completed preparations for a ground invasion of the Gaza Strip as air raids on sites connected to the militant group Hamas entered their fourth day.

"The ground forces are ready," an army spokeswoman said. "The option (of a ground operation) exists. It is possible that we will apply it but for the moment we are only hitting from the air and the sea."

Israel on Tuesday rejected any truce with Hamas until Palestinian militants stopped firing rockets into Israel and said its air strikes heralded "long weeks of military action."

On the fourth day of the air raids, at least 10 Palestinians were killed, including two sisters aged 10 and 12. Medical officials put Palestinian casualties since Israel launched its attacks on Saturday at 348 dead with more than 800 wounded. A United Nations agency said at least 62 of the dead were civilians. Four Israelis -- three civilians and a soldier -- have been killed by Palestinian rockets since the air strikes began.

Israeli media quoted Prime Minister Ehud Olmert as saying the Gaza operation was in "the first of a several stages."

The United Nations has called for an immediate truce. But Israeli Interior Minister Meir Sheetrit said "there is no room for a cease-fire" with Hamas until the threat of rocket fire had been removed. "The Israeli army must not stop the operation before breaking the will of the Palestinians, of Hamas, to continue to fire at Israel," he told Israel Radio.

Hamas spokesman Fawzi Barhoum has urged Palestinian groups to respond using "all available means" against Israel, including "martyrdom operations," which means suicide bombings.

The attacks are deepening divisions among Arab states. On Tuesday the Syrian leadership called on Egypt to break off diplomatic relations with Israel. Daily newspaper Tishreen, which is loyal to the Syrian government, wrote that Egypt "should return to its proper role as an Arab country that faces up to the political battle against Israel on the Palestinian issue." Many Arab countries are accusing Egypt of having agreed to the Israeli attacks on the Gaza Strip.

The issue has proven difficult for Muslims also because the Palestinians themselves are divided. Hamas took over control of the Gaza Strip in June 2007 from the Fatah Party loyal to Palestinian Authority President Mahmoud Abbas. The international community has sought to isolate Hamas and has refused to establish diplomatic relations with the group.

Concern about Press Freedom

Meanwhile foreign journalists in Israel are petitioning the country's highest court to let them into Gaza to report on the fighting. The ban has been in place for about two months, and has been lifted only occasionially during that time.

The petition was submitted on Sunday by the Foreign Press Association, which represents journalists covering Israel, the West Bank and Gaza. The court will hear the petition on Wednesday. Most of the current news footage from Gaza is being supplied by Palestinian journalists working for news agencies and for Arab news channels.

Ethan Bronner, correspondent for the New York Times, said Israel was breaching its own principles of press freedom by refusing to let foreign reports into Gaza. "They say they have security concerns -- but they have also made clear that they aren't happy with the reporting by international media," he said.

Schlomo Dror, spokesman for the Israeli Defense ministry, recently told the New York Times that he wasn't shedding any tears at the journalists' frustration. Israel had regarded much of the prior reporting from Gaza as unfair, he said.

Since Monday journalists can't even get close to the Gaza Strip. An area several kilometers wide around the border has been declared a restricted zone.