Israel largely captured the northern half of Gaza in November, and has swiftly pushed deep into the southern half since the weeklong truce collapsed on Friday. The Gazan health ministry said about 900 Palestinians have been killed since Friday.

Hamas ally Islamic Jihad's armed wing said its fighters engaged in fierce clashes with Israeli soldiers north and east of Khan Younis, Gaza's main southern city.

Israeli tanks have driven into Gaza across the border and cut off the main north-south route, residents said. The Israeli military said the central road out of Khan Younis to the north "constitutes a battlefield" and is now shut.

In eight weeks of conflict, the Gazan health ministry said at least 15,899 Palestinians have been killed and 70 percent of them were women or children under the age of 18.