GAZA: Israeli troops have launched a ground operation in the northern Gaza Strip, the first since the offensive against Hamas began, as Palestinian deaths continue to mount. The navy commandos’ brief incursion - which ignored a United Nations call for a ceasefire - targeted a rocket launcher site, according to Israeli public radio.

The armed branch of Hamas confirmed that Israeli troops had exchanged gunfire with Palestinian fighters. Thousands of residents in northern Gaza have fled their homes, after a warning from Israel’s military that they should leave “for their own safety.”

Palestinian President Mahmoud Abbas is to ask the United Nations for international protection as the six-day offensive continues.

The Palestine Liberation Organisation said in a statement, “President Abbas will present a letter to the UN Special Coordinator for the Middle East Peace Process, Robert Serry, addressed to UN Secretary General Ban Ki-moon, to officially put the State of Palestine under the UN international protection system and to form a legal committee for immediate follow-up.”

Israel says it plans to step up its offensive against Hamas militants in Gaza over the next 24 hours in an effort to stop missiles being fired into Israel. It has been massing military hardware and troops close to the border with northern Gaza.

Sky’s Alex Rossi said more than 100 Israeli armoured personnel carriers and tanks are in the area. Israel began its offensive on Tuesday in response to weeks of rocket attacks from Hamas militants in Gaza, who are understood to have fired more than 600 missiles into the country.

Two more rockets shot from Gaza were destroyed over the Tel Aviv area by the Iron Dome missile defence system on Sunday, several hours after another two rockets were intercepted over Lod, close to the country's main airport. Hamas has denied being behind a rocket attack on Israel from Lebanon on Saturday evening.

Earlier that day an Israeli warplane bombed the home of Gaza's police chief and damaged a nearby mosque, killing at least 18 people and wounding 50. It was the deadliest single attack during the five-day conflict, which has now claimed 165 Palestinian lives and left more than 1,000 injured.

The injured were taken to al Shifa hospital in Gaza City as the bombardment continued. Dr Ayman al Sahabany, director of emergency ward at the hospital, said: "Women and children are more than half of the casualties. And children form a third of the total casualties."

No Israelis have died so far in the latest conflict, and many of the rockets fired into the country have been intercepted by Iron Dome. Speaking before an international summit in Vienna, British Foreign Secretary William Hague said there was an "urgent need" to stop the bloodshed.