Washington ? The Bush administration on Saturday blamed the more than week-old onslaught in Gaza squarely on Hamas militants, but did not mention the invasion of Israeli ground troops into Gaza and avoided any criticism of Israel despite mounting world outrage over the growing death toll.

Israel launched the ground assault on Gaza on Saturday in its bid to stop Hamas rocket attacks.

A State Department official said the U.S. is working toward a cease-fire but provided no details on how this can be accomplished because the U.S. does not talk to Hamas. Spokesman Sean McCormack said a cease-fire is needed that will not allow Hamas to continue firing rockets into Israel. McCormack said “it’s obvious the cease-fire should take place as soon as possible,” but it has to be sustainable and cannot allow Hamas to continue to launch rockets out of Gaza.

The U.N. Security Council held emergency consultations Saturday night to address the escalation of violence in Gaza, and Secretary-General Ban Ki-moon urged an immediate halt to Israel’s ground operation. Arab nations demanded that the Security Council call for an immediate cease-fire.

The United States late Saturday blocked approval of a Security Council statement calling for an immediate cease-fire in the Gaza Strip and southern Israel and expressing concern at the escalation of violence between Israel and Hamas. U.S. officials said there was little chance Hamas would adhere to the statement, based on the group’s earlier response to such calls for a cease-fire.

President George W. Bush was briefed Saturday afternoon on the situation in Gaza and White House spokesman Gordon Johndroe said U.S. officials are in “regular contact with the Israelis as well as officials from countries in the region and Europe.”

Asked if the U.S. was warned before the invasion, Johndroe did not answer that question, but said: “Their ground action is part of their overall operation. We continue to make clear to them our concerns for civilians, as well as the humanitarian situation.”

A senior U.S. defense official in Washington said it appeared that the Israeli ground force that entered Gaza consisted of perhaps two brigades, equating to roughly several thousand troops.