At least seven Palestinians have been killed during further Israeli air strikes in Gaza.
An attack on a Hamas stronghold in the Zeitun neighbourhood of Gaza City left four militants dead. They were hit by what local officials said appeared to be at least one missile from an F-16 jet.
And at least one man died and five others were wounded when Israeli helicopter gunships fired on a group allegedly launching rockets into Israel.
Two more Palestinians were killed when their minibus was hit in another air strike this afternoon.
The Israeli intervention in Gaza has further complicated an already tense situation, with at least 48 Palestinians killed in clashes between Hamas and Fatah since Sunday.
Around a dozen Israeli tanks have now advanced across the border into Gaza and the army has redeployed artillery facing the coastal strip for the first time since a truce in late November.
The Jewish state said its actions were in response to renewed rocket attacks on Israel, which have been seen as an attempt to draw it into the ongoing factional conflict in Gaza.
The violence has prompted international concern and appeals for calm, with US President George W Bush urging all parties to work 'toward a two-state solution'.
Meanwhile, gun battles have continued on the streets of Gaza City, despite a fourth ceasefire in four days.
Fatah leader and Palestinian President Mahmoud Abbas had been due to hold peace talks with Prime Minister Ismail Haniyeh of Hamas yesterday, but the planned visit to Gaza City was called off after an apparent assassination attempt by Hamas.
Fatah security officials accused their unity government partners of attempting to kill Mr Abbas following the discovery of explosives on the route the Palestinian President was to take.
The Palestinian unity cabinet took office on 17 March following a Saudi-mediated deal, but its future is now in doubt. The current unrest was sparked by the murder of a Hamas member on Sunday.
