Israel is continuing to hammer Hamas targets in the Gaza Strip, and Palestinian health officials say over 225 people have been killed so far.

Israeli jets and helicopters hit security compounds and buildings in a wave of strikes which began just after midday local time and continued into the night.

Israel said more than 100 tonnes of bombs were dropped on dozens of targets in two intense waves of airstrikes.

There were many civilian casualties, as well as some top Hamas officials. Emergency services were overwhelmed and bodies were dumped in piles outside the main hospital. Frantic crowds gathered to look for loved ones amongst the dead.

Gaza has not seen so many casualties in a single day since the 1967 Arab-Israeli war.

Israel says the strikes are in response to almost daily rocket fire by Gaza militants, which has intensified since Hamas ended a six-month-old ceasefire a week ago and killed an Israeli man in the town of Netivot overnight.

Israeli leaders say the air raids are against Hamas and not the people of Gaza, and only military targets have been selected.

Exiled Hamas leader Khaled Meshaal called in Damascus for a new Palestinian intifada, or uprising, against Israel and promised new suicide attacks.

Meshaal called for a “military intifada against the enemy” and said “resistance will continue through suicide missions.”

In a televised address, the leader of the Hamas administration in Gaza, Ismail Haniyeh, called the attack a massacre.

“There is an Israeli plan behind this ugly massacre, the like of which Palestine has never witnessed,” he said.

“By targeting those innocent youths, children, women and the elderly, this plan aims to destroy an historic resistance. Even if you killed thousands of us, you would never kill our pride and our resolve.”

Israeli Defence Minister Ehud Barak told Fox News that Israel “cannot really accept” a ceasefire with Hamas.

“For us to be asked to have a ceasefire with Hamas is like asking you to have a ceasefire with al Qaeda. It’s something we cannot really accept,” he said in an interview from Tel Aviv.

Asked whether Israel would follow up the air strikes with a ground offensive, Mr Barak said, “If boots on the ground will be needed, they will be there.”

“Our intention is to totally change the rules of the game,” he said.

Death toll rises as Hamas vows revenge – ABC News (Australian Broadcasting Corporation)