The United States has asked Israel for an explanation over the heavy Palestinian casualties caused by its massive military operation in the Gaza Strip, White House spokesman Scott McClellan said at a news briefing on Wednesday.

"We have asked for an explanation from the government of Israel.We want to know what has happened or what happened, how this happened. We have been told that Israel is investigating, and we expect to receive an explanation as soon as that investigation is completed," McClellan said.

"We share the view of the Israeli government that this was a tragic event, and we agree with their comments that -- expressing deep regret for what occurred," McClellan said.

However, McClellan chose not to condemn Israel, a key US ally in the Middle East, and only urged the Jewish state "to keep in mind the consequences of their actions."

Israel faced worldwide condemnation over its military operationin the Gaza Strip as another 10 Palestinians were killed Wednesday hen Israel opened fire on a demonstration in the area of Rafah refugee camp in the southern Gaza Strip. As many as 20 Palestinians were killed on Tuesday in Israel's Operation Rainbow,the largest Israeli incursion into the Gaza Strip since the Palestinian uprising began nearly four years ago.

Source: Xinhua