Israeli warplanes swung into action over south Beirut, dropping 20 tonnes of bombs on a suspected Hezbollah leadership bunker and its ground troops were locked in fierce fighting with militants after launching another cross-border raid.
Hezbollah claimed it had destroyed two tanks while Israeli television reported two soldiers had been injured.
But the target which 20 Israeli war planes were sent to bomb has been disputed. Israel says it attacked what it believed to be a Hezbollah leadership bunker but the militant group, denying that any of its members had been killed, said the building was a mosque.
"The country has been torn to shreds. Can the international community stand by while such callous retribution by the state of Israel is inflicted on us?" Lebanese Prime Minister Fuad Siniora told a gathering of foreign ambassadors.
"You want to support the government of Lebanon? Let me tell you... no government can survive on the ruins of a nation," he said. "I hope you will not let us down. We the Lebanese want life. We have chosen life. We refuse to die."
Highest death toll
Israel’s continuing campaign to crush Hezbollah saw 72 people killed Wednesday, the highest single day death toll since the offensive was launched. It launched a massive blitz from the air and sea against southern and eastern Lebanon, reportedly flattening houses, destroying roads and hitting trucks.
Meanwhile, concerns are mounting over the humanitarian crisis, with the United Nations warning of an impending "catastrophe." For many Lebanese there is little chance of fleeing the country. Police say about 70 percent of the population of south Lebanon, have fled their homes to find safer places.
The UN High Commissioner for Human Rights Louise Arbour has warned that the perpetrators, of this conflict, could be held to account for war crimes.
Israel’s offensive is also drawing criticism from The International Committee of the Red Cross (ICRC), "The high number of civilian casualties and the extent of damage to essential public infrastructure raise serious questions regarding respect for the principle of proportionality in the conduct of hostilities," ICRC director of operations Pierre Kraehenbuehl said.
International discussions
US Secretary of State Condoleezza Rice and the European Union’s foreign policy chief Javier
Solana were to meet in New York on Thursday with UN chief Kofi Annan. Mr Solana told the BBC that he hoped the conflict could be over by the end of next week.
"We will work very, very hard to see if we can have an end of hostilities and the beginning of something of a political nature before the end of next week."
But there are no signs of a ceasefire, with Israel vowing after a security cabinet meeting that its “intensive war” against Hezbollah would go on for as long as it deemed necessary.