Ian Bruce and Carolyn Churchill

US President Elect Barack Obama broke his silence about the Gaza war last night after Israeli tank shells reportedly killed more than 30 Palestinians, including a number of children, at a UN school where civilians had taken shelter.

The Israeli army said troops fired mortars at the premises after gunmen mortared their positions from inside al Fakhora school in Jabalya refugee camp. Witnesses said two shells exploded outside the school, killing and wounding dozens of people who had sought refuge or were residents of nearby buildings.

Speaking after the latest attack, Mr Obama said "the loss of civilian life in Gaza and in Israel is a source of deep concern for me" and pledged to work for a resolution to the conflict.

"After January 20 I'm going to have plenty to say about the issue, and I am not backing away at all from what I said during the campaign, that starting at the beginning of our administration, we are going to be engaged effectively and consistently in trying to resolve the conflict in the Middle East," he said.

Last night Venezuela added its weight to demands for a ceasefire, ordering Israel's ambassador to be expelled from the country.

The decision by President Hugo Chavez appeared to be the strongest reaction yet by any country with ties to Israel.

Earlier, al Qaeda's second-in-command, in an internet message, said that Israeli attacks on Gaza were part of a Western campaign against Islam and accused Mr Obama of complicity.

"What you are facing now is a link in a chain in the Zionist crusader campaign on Muslims and Islam," Ayman al Zawahri said in an audio tape posted on Islamist websites. "These attacks are Obama's present to you (Palestinians) before he takes office."

Speaking last night, Prime Minister Gordon Brown warned that the Middle East was facing its "darkest moment yet" but expressed hope that a deal could be struck for an immediate ceasefire.

Israel, meanwhile, said it would set up a "humanitarian corridor" for the Gaza Strip.

Prime Minister Ehud Olmert's office said the corridor had been recommended by Israel's military chiefs and would entail granting periodic access to various areas of the strip so Palestinians could stock up on vital goods. A spokesman said it could be implemented today.

Aid agencies have complained of a mounting crisis for the strip's 1.5 million residents.

It also emerged last night that Israeli military units could begin withdrawing from the Gaza Strip within the next 72 hours to end Operation Cast Lead's assault on Hamas militants inside the crowded Palestinian coastal enclave.

An Israeli Defence Force official told The Herald that if scheduled operations went to plan, troops and tanks could be pulling back inside their own borders by the weekend.

The explosion at the al Fakhora school marked the second time in hours that a UN school had come under attack and it was the deadliest assault since Israel sent ground forces into Gaza last weekend as part of a larger offensive against the ruling Hamas militant group.

More than 600 Palestinians are thought to have been killed, according to local hospital officials, and UN and Palestinian officials have estimated that nearly half of the dead are civilians.

Click here to comment on this story...