An Israeli air strike killed at least 40 Lebanese civilians, including 23 children, yesterday, prompting Lebanon to tell US Secretary of State Condoleezza Rice she was unwelcome in Beirut before a ceasefire. Hundreds of protesters chanting ?Death to Israel, Death to America? stormed the UN headquarters in Beirut, even though witnesses said Hizbollah officials tried to discourage them.

Rice, who plans to stay on in Israel, said she was deeply saddened by the air raid on the southern village of Qana, but stopped well short of calling for an immediate ceasefire. It was the bloodiest single attack during Israel?s 19-day-old war on Hizbollah guerrillas.

Hizbollah vowed to retaliate. ?This horrific massacre will not go without a response,? it said in a statement. Lebanese Prime Minister Fouad Siniora said he would not hold negotiations before a ceasefire and officials said they had told Rice her planned visit to Beirut could not go ahead.

The dawn air raid pulverized several buildings in Qana, including a three-storey house in which dozens of displaced civilians were sheltering, killing many people in their sleep. A Reuters witness counted 40 bodies and rescuers said the death toll might rise to 55. Lebanese Red Cross officials in Beirut said 23 children were among the dead and that at least 17 more bodies were feared to be still under the rubble, seven of them children.

Demonstrators carrying Lebanese and Hizbollah flags attacked the UN headquarters in downtown Beirut, ransacking offices and tearing down a United Nations flag and ripping it to shreds.

Siniora denounced ?Israeli war criminals?. He demanded an immediate, unconditional ceasefire and an international investigation into ?Israeli massacres?. Rice said it was ?time to get to a ceasefire,? confirming she would not go to Beirut but would stay in Jerusalem. ?My work toward a ceasefire is really here today.?

But she reiterated that a ceasefire could not mean a return to the status quo before the war, which began after Hizbollah seized two Israeli soldiers in a cross-border raid on July 12. Earlier, Israeli Prime Minister Ehud Olmert told a weekly cabinet meeting: ?Israel is in no rush to reach a ceasefire before we get to that point where we could say that we reached the main objectives we had set forth. This includes the ripening of the diplomatic process and preparing the multinational force.?

The United States says the priority is to remove the threat posed to Israel by Hizbollah, which is backed by Iran and Syria. The Qana air strike occurred as Rice was in Jerusalem on a mission to get Israel and Lebanon to agree on an international force to deploy on the border as part of a ceasefire deal.

Olmert said Israel had told Qana residents to leave before the raid, saying Hizbollah had fired rockets at Israel from the village and its environs. Israeli forces thrust across the border overnight, sparking clashes with Hizbollah guerrillas.

French President Jacques Chirac condemned the Qana bombing and said it underlined the need for an immediate ceasefire. Jordan?s King Abdullah called it an ?ugly crime.?

Grief and anger

Distraught people in Qana screamed in grief and anger amid wrecked buildings as others scrabbled at slabs of concrete with their hands to try to reach people buried in the debris. Red Cross workers covered the corpse of one dead child with a blanket. A woman in a red-patterned dress lay crumpled and lifeless in the broken masonry. A leg poked out from the rubble nearby. Another child lay dead in the street.

?All the residents were warned and told to leave. No one was ordered to fire on civilians and we have no policy of killing innocent people,? Israeli media quoted Olmert as saying. Israeli warplanes struck Qana only hours after Hizbollah leader Sayyed Hassan Nasrallah threatened to rocket more cities in central Israel if attacks on Lebanon continued.

Qana is already a potent symbol of Lebanese civilian deaths at the hands of the Israeli military. In April 1996, Israeli shelling killed more than 100 civilians sheltering at the base of UN peacekeepers in the village during Israel?s ?Grapes of Wrath? bombing campaign.

At least 523 Lebanese, mostly civilians, and 51 Israelis have been killed in the latest conflict. Confirming a major new incursion into Lebanon, the Israeli military said tanks and troops had rolled across the border at Metula, under cover artillery fire and air strikes, to try to find and destroy Hizbollah rocket launchers.

An Israeli army spokeswoman said at least one soldier had been wounded in fighting, in which she said Hizbollah had lost five dead. Hizbollah reported fierce clashes.