Israel has pushed ahead with its offensive in Gaza, ignoring a UN Security Council resolution calling for an immediate ceasefire.
UN highlights reports of civilian shelter bombing - more
More than 50 air strikes have taken place in Gaza since yesterday evening.
Palestinian emergency services said 12 civilians were killed in the raids, taking the death toll to almost 800.
Medics said half died when tanks shelled a house in Beit Lahiya in the north of Gaza, killing six from the same family.
Hamas and its allies have fired more than 15 rockets into southern Israel in further attacks today, injuring one person.
Israeli Prime Minster Ehud Olmert said: 'Israel has never agreed for any outside influence to decide on its right to defend its citizens.
'The IDF (Israel Defence Forces) will continue to operate in order to defend the citizens of Israel and will carry out the task it was given for the operation.
'The firing of rockets this morning only goes to show that the UN decision is unworkable and will not be adhered to by the murderous Palestinian organisations,' he said.
UN Secretary-General Ban Ki-moon has told Mr Olmert that he was disappointed that the Security Council resolution had so far been ignored.
A Hamas official in Beirut, Raafat Morra, said his group was also rejecting the UN resolution, as it was not in the best interest of the Palestinian people.
Pressure on Israel increased with the UNSC resolution, which demands an immediate, durable ceasefire leading to the full withdrawal of Israeli forces from Gaza.
The US abstained - but refrained from vetoing the resolution agreed by foreign ministers after lengthy negotiations.
US Secretary of State Condoleezza Rice said her country abstained because the US wanted to see the outcome of a peace initiative by Egyptian President Hosni Mubarak.
Mr Mubarak has invited Israel and Palestinians to Cairo for talks on truce conditions.
The resolution, pressed for by Arab countries in the face of efforts by Britain, France and the US for a more muted statement, called for arrangements to prevent arms smuggling into Gaza and for its borders to be opened.
Israel has been strongly criticised by UN agencies, the Red Cross and other aid groups.
The text called for the unimpeded provision and distribution throughout Gaza of humanitarian assistance, including food, fuel and medical treatment.
The UN Relief and Works Agency, which distributes the vast majority of aid in Gaza, has kept its operations suspended after the death of a driver in Israel's offensive.
Elsewhere, two Fianna Fáil TDs have tabled a motion inviting a UN representative to appear before the joint Oireachtas Committee on European Affairs to report on the situation in Gaza
Timmy Dooley and Michael Mulcahy said the committee would have to decide whether there had been a breach of the human rights section of an EU-Israel trade agreement and testimony from the UN experts would be central to their deliberations.
