The United States is deeply concerned over the humanitarian situation in the Gaza Strip, urging Israel to avoid causing civilian casualties during its military strikes against Palestinian militants, US State Department said on Saturday.

"The United States is deeply concerned about the humanitarian situation and the protection of innocents," said spokesman Sean McCormack, adding "any military action needs to be mindful of the potential consequences to civilians."

His remark came hours after Israel's ground troops entered the Gaza Strip ruled by Islamic Resistance Movement (Hamas) for the second phase of offensive on the militant group after a week of air strikes.

The military offensive, aimed at retaliating for Hamas militant rocket attacks into Israel, have killed at least 460 Palestinians and wounded 2,750 others in the past week. Meanwhile, four Israelis were killed and 59 others wounded in Hamas rocket attacks, CNN quoted medics from both sides as saying on Saturday.

"We are working toward a cease-fire that would not allow a re- establishment of the status quo ante, where Hamas can continue to launch rockets out of Gaza and to condemn the people of Gaza to a life of misery," said the spokesman.

"It is obvious that that cease-fire should take place as soon as possible, but we need a cease-fire that is durable, sustainable, and not time limited," McCormack said.

US President George W. Bush was briefed Saturday afternoon on the situation in the Gaza Strip and Israel's military actions there, the White House said, adding "US officials have been in regular contact with the Israelis as well as officials from countries in the region and Europe."

(Xinhua News Agency January 4, 2009)