China has renewed its call to the Israeli government and Hamas to cease fire in the Gaza Strip, as the civilian death toll rose to more than 500 following Tel Aviv's ground offensive.

The escalating violence in Gaza is a cause of great worry for China, President Hu Jintao said yesterday over the phone with his US counterpart George W. Bush.

China urges both sides to immediately stop military action to prevent civilian casualties and take steps to ease the humanitarian crisis in Gaza, he said.

Hu's remark came after Israeli tanks and troops launched a ground attack on the Gaza Strip on Saturday night. The rhetoric on both sides is strong, with Israeli officials saying they expect a long fight with Hamas militants, and the latter vowing to make Gaza a "graveyard" for Israel's forces.

Tel Aviv said it launched the ground offensive after eight days of air strikes on the Palestinian territory failed to stop rocket attacks on Israel.

The air strikes have left more than 500 Palestinians dead, while Hamas rockets have killed four Israelis.

Gaza is densely populated, and an intense urban war could lead to a much higher civilian toll, with the UN estimating that at least a quarter of the Palestinians killed are civilians.

The Chinese embassy in Palestine said it had prepared an emergency plan, but was not thinking of leaving the country, an embassy official surnamed Wang said yesterday.

"The situation is harsh, and it's still hard to say whether the war will expand to the West Bank," Wang said.

Negotiations are the only way to end the conflict in the region, said Zhang Xiaodong, secretary-general of the China Association of Middle East Studies. "A humanitarian crisis is looming with many civilians falling victim to the attacks."