The UN coordinator said the humanitarian crisis in the region was "dramatic" though relief efforts were being stepped up.
Mr Egeland said he had proposed the truce to the UN Security Council on Friday and would approach Israel and the Lebanese group, Hezbollah, to agree to the humanitarian cessation of hostilities.
"I will again go back to the parties, to the Israelis, to the Lebanese, and ask for at least a 72 hour start of this cessation of hostilities so that we can evacuate the wounded, evacuate children, the elderly, the disabled from the crossfire in southern Lebanon,” he said.
He was speaking after briefing the Security Council on the humanitarian situation in the Middle East after returning from a six-day mission to the region.
"The truce would be a period in which we can get generalised access to the people and that those who want to escape can escape in safety," he said, estimating that many thousands of people still wanted to get out of the conflict zone.
Mr Egeland said hospitals and clinics would be resupplied and "emergency medical assistance" would be given to the wounded and food delivered to the tens of thousands of displaced.
He said that humanitarian workers were "stepping up" their work and, awaiting security guarantees and safe routes for convoys, will be able to provide 10,000 to 20,000 tonnes of food in Lebanon in the next month.
Mr Egeland said he also wanted to set up a communications link to the isolated villages, where contact has been lost due to the fighting and infrastructure damage.
UN Secretary General Kofi Annan has made repeated calls for a permanent cessation of hostilities, which has so far been rejected.
The conflict, which erupted July 12, has left more than 600 dead in Lebanon alone, according to Mr Egeland, and hundreds of thousands have fled their homes in south Lebanon. He estimated that at least one third of the casualties were children.
Lebanese authorities say that at least 437 Lebanese have been killed, including 382 civilians confirmed dead by the health ministry. In addition, 20 Lebanese soldiers and at least 35 Hizbollah guerrillas have been killed.
The Lebanese health minister also says 58 others are known to be buried under the rubble of buildings and 150 more are missing, believed dead.
Some convoys have gone to Beirut with staff still shaken from the four UN observers killed at an outpost on the Israeli border, the UN humanitarian chief reported.
In his report to the Security Council, Mr Egeland said he "urged the foreign minister and defence minister of Israel in my meetings to review the conduct of the air strikes and bombardments to avoid excessive use of force" on civilians.
"At the same time, I repeatedly and publicly appealed from within Lebanon that the armed men of Hizbollah must stop their deplorable tactic of hiding ammunition, arms or combatants among civilians," he said.
"There is something fundamentally wrong with a war where there are more dead children than armed men. That has to stop. There has been too much suffering in Lebanon, in northern Israel and in Gaza -- which is becoming the forgotten conflict in the Middle East,” Mr Egeland said.
At least 145 Palestinians and one Israeli soldier have died since Israel launched a massive offensive in late June to recover a soldier captured by Gaza militants and halt rocket fire from the coastal strip, according to a count by news agency AFP.
Mr Egeland said the United Nations had raised US$15 million, out of the US$150 million it needs for operations in Lebanon.