There has been no let-up in the fighting overnight between Israel and Hamas militants in the Gaza Strip, with both sides launching strikes into the other's territory.
There is speculation over a possible Israeli ground offensive in Gaza: with reports of a build-up of troops near the border.
Israel's "Pillar of Defence" operation is into its third day as it continues to respond to rockets fired by Hamas militants.
The first 48 hours of airstrikes have left at least 19 Palestinians dead in Gaza. Civilians, including six children, were among those killed.
However Israeli Prime Minister Benjamin Netanyahu has said that the military offensive will be suspended during the visit to Gaza by Egypt's prime minister on Friday.
The exchange of firepower is matched by a war of words. Hamas has warned that Israel will pay dearly for what Prime Minister Ismail Haniyeh called a "ferocious assault" on the Palestinian territory.
Israel is authorising the call-up of 30,000 reservists. The Defence Minister Ehud Barak said Hamas would have to pay the price for targeting Tel Aviv.
The first missile threat on Israel's commercial capital in 20 years has shaken the country.
Two Hamas rockets landed in the area after being launched from Gaza 70 kilometres to the south.
Hamas claims to have fired hundreds: in one town nearer the border three Israeli civilians were killed when their block of flats was hit.
Israel claims its Iron Dome missile defence system has intercepted over 100 rockets.
Government spokesmen said Israel was not interested in a ceasefire, but in continuing its offensive until Hamas "begs for one".
