At least four Palestinians have been killed by Israeli tank fire nearly two hours after Israel and Hamas began observing a three-day ceasefire, Gaza officials have said.

Israeli aircraft have struck 30 houses in the Gaza Strip, killing a leader of the militant Islamic Jihad group and two of his sons.

Israeli air strikes pummelled a wide range of targets in the Gaza Strip today as the UN chief and the US Secretary of State began an intensive effort to end more than two weeks of fighting that has killed at least 570 Palestinians and 29 Israelis.