Israeli tank shells hit a compound housing a UN school in the Gaza Strip, killing at least 15 people and wounding dozens who were seeking shelter from fierce clashes on the streets outside.

The overall Palestinian death toll passed 560 as high-level attempts to end Israel-Hamas fighting hit serious problems.

The UN chief and the US secretary of state are heading to Cairo to try to end two weeks of Israel-Hamas fighting in Gaza which has killed at least 500 Palestinians and 20 Israelis and displaced tens of thousands of people.

Israeli troops have uncovered more than a dozen cross-border tunnels and battled Gaza militants on the second day of a ground operation, as the Palestinian death toll climbed past 330 and diplomats scrambled to revive ceasefire efforts.

Israel has widened its range of Gaza bombing targets to civilian institutions with suspected Hamas ties and announced it would hit northern Gaza "with great force" to prevent rocket attacks from there on Israel.

An Israeli missile ripped through a two-story home in a residential area of Gaza City on Sunday, killing at least 11 civilians, including four young children and an 81-year-old woman, in the single deadliest attack of Israel’s offensive against Islamic militants.

An Israeli missile flattened a two-story house in a residential neighbourhood of Gaza City today, killing at least 11 civilians, medical officials said.

Israeli strikes hit two media centres in the Gaza Strip today as Israel warned it was widening its range of targets to go after military commanders of the territory’s Hamas rulers.