ISRAELIIsraeli jets have attacked the Gaza Strip for a fourth day, with raids on a number of Hamas government buildings and security installations.
Air strikes early on Tuesday killed at least 10 people, medical officials in the coastal enclave said.
UN Secretary General Ban Ki-moon has called for an immediate ceasefire and condemned both Israel and Hamas.
About 320 Palestinians have died since Saturday, the UN says. Four Israelis have been killed by rockets from Gaza.
One was a soldier, the first member of the military to die since the current fighting began.
While recognising Israel's right to defend itself from militant rocket attacks, Mr Ban condemned its "excessive use of force".
See detailed map of attacks
"The suffering caused to civilian populations as a result of the large-scale violence and destruction that have taken place over the past few days has saddened me profoundly," he said.
'Bitter end'
Forty people were said to have been wounded in Tuesday's raids, which targeted Hamas-run offices and security installations, Palestinian officials said.
Israel's defence chief earlier said his country was fighting a "war to the bitter end" against Hamas.
The UN says at least 62 of the Palestinians killed so far have been women and children.
Israel has massed forces along the boundary with Gaza and has declared the area around it a "closed military zone".
Correspondents say the move - in addition to the call-up of thousands of reservists - could be a prelude to ground operations, but could also be intended to build pressure on Hamas.
The Red Cross earlier described the situation in Gaza's hospitals as chaotic, with medical teams "stretched to the limit".
Trucks laden with medical aid have been permitted to cross into Gaza from Egypt at the Rafah crossing.
European Union foreign ministers are scheduled to to meet in Paris later (1730 GMT) to discuss the escalating crisis.
The meeting, hosted by French Foreign Minister Bernard Kouchner, is expected to consider the idea of an humanitarian aid corridor, and how to bring additional aid to Gaza.
Angry protests
Dozens of centres of Hamas strength, including security compounds, government offices and tunnels into Egypt, have been hit since Israel started its massive bombing campaign on Saturday morning.
Israel says its aim is to end the rocket attacks by Hamas-linked militants - of which there were reportedly more than 40 on Monday.
Defence Minister Ehud Barak said Israel wanted to deal Hamas a "severe blow" and its operation would be "widened and deepened as needed".
The US - Israel's strongest ally - said the onus was on Hamas to end the violence and commit itself to a truce, but there have been angry protests against the offensive in many cities across the Arab world and in several European capitals.
The strikes began less than a week after the expiry of a six-month-long ceasefire deal with Hamas, which has controlled Gaza since 2007.
Israel withdrew in 2005 but has kept tight control over access in and out of Gaza and its airspace.
BBC
Air strikes early on Tuesday killed at least 10 people, medical officials in the coastal enclave said. UN Secretary General Ban Ki-moon has called for an immediate ceasefire and condemned both Israel and Hamas.
About 320 Palestinians have died since Saturday, the UN says. Four Israelis have been killed by rockets from Gaza.
One was a soldier, the first member of the military to die since the current fighting began.
While recognising Israel's right to defend itself from militant rocket attacks, Mr Ban condemned its "excessive use of force".
See detailed map of attacks
"The suffering caused to civilian populations as a result of the large-scale violence and destruction that have taken place over the past few days has saddened me profoundly," he said.
'Bitter end'
Forty people were said to have been wounded in Tuesday's raids, which targeted Hamas-run offices and security installations, Palestinian officials said.
Israel's defence chief earlier said his country was fighting a "war to the bitter end" against Hamas.
The UN says at least 62 of the Palestinians killed so far have been women and children.
Israel has massed forces along the boundary with Gaza and has declared the area around it a "closed military zone".
Correspondents say the move - in addition to the call-up of thousands of reservists - could be a prelude to ground operations, but could also be intended to build pressure on Hamas.
The Red Cross earlier described the situation in Gaza's hospitals as chaotic, with medical teams "stretched to the limit".
Trucks laden with medical aid have been permitted to cross into Gaza from Egypt at the Rafah crossing.
European Union foreign ministers are scheduled to to meet in Paris later (1730 GMT) to discuss the escalating crisis.
The meeting, hosted by French Foreign Minister Bernard Kouchner, is expected to consider the idea of an humanitarian aid corridor, and how to bring additional aid to Gaza.
Angry protests
Dozens of centres of Hamas strength, including security compounds, government offices and tunnels into Egypt, have been hit since Israel started its massive bombing campaign on Saturday morning.
Israel says its aim is to end the rocket attacks by Hamas-linked militants - of which there were reportedly more than 40 on Monday.
Defence Minister Ehud Barak said Israel wanted to deal Hamas a "severe blow" and its operation would be "widened and deepened as needed".
The US - Israel's strongest ally - said the onus was on Hamas to end the violence and commit itself to a truce, but there have been angry protests against the offensive in many cities across the Arab world and in several European capitals.
The strikes began less than a week after the expiry of a six-month-long ceasefire deal with Hamas, which has controlled Gaza since 2007.
Israel withdrew in 2005 but has kept tight control over access in and out of Gaza and its airspace.
BBC