Hezbollah's capture of two Israeli soldiers last week was timed to divert attention from Tehran's nuclear programme, the Israeli PM has claimed.
Israel launched its assault and blockade a week ago
Ehud Olmert said that the cross-border raid in which the two soldiers were captured was co-ordinated with Tehran.
About 30 people died in a seventh day of conflict, most of them in Lebanon.
US President George W Bush has meanwhile accused Syria of trying to use the crisis to deepen its influence in Lebanon.
"Syria is trying to get back into Lebanon, it looks like to me," Mr Bush said in Washington.
"It's essential that the government of Lebanon survives this crisis. We've worked hard to free - and we meaning the international community - worked hard to free Lebanon from Syrian influence."
The US state department refused to confirm comments by an Israeli ambassador that Secretary of State Condoleezza Rice would travel to the region on Friday.
Israel launched its assault and blockade last Wednesday after the two soldiers were captured.
About 230 Lebanese people have been killed since then - the majority of them were civilians, but the toll includes about 30 soldiers. The number of Hezbollah militants killed is not known.
Twenty-five Israelis have died - 13 civilians and 12 members of the military.
The human cost of the crisis has continued to mount
Israel has frequently blamed Syria and Iran for arming and backing Hezbollah, but Mr Olmert's comments were the first explicit claim of Tehran's direct involvement in the capture of the soldiers, correspondents say.
Mr Olmert said the timing of the incident was not an accident, and the international community at the G8 summit in Russia had fallen for it - discussing Lebanon rather than Iran's nuclear programme.
Earlier, Israel's foreign minister met a UN team trying to negotiate a ceasefire, but said the soldiers' release and the deployment of the Lebanese army in the south would have to precede any ceasefire.
Thousands more foreigners have continued to flee Lebanon as the crisis deepens.
The UN announced that its non-essential staff would join the exodus.
A British warship is currently on its way to Cyprus, carrying the first Britons to be evacuated from Lebanon by sea.
HMS Gloucester picked up 180 of the most needy cases, including children, after docking in Beirut. Up to 5,000 more Britons are expected to follow over the next few days. The US, Canada and other governments were also organising evacuations by land, air or sea.
In other developments:
- Lebanese PM Fouad Siniora said Israel was "opening the gates of hell and madness" on his country, and said Israel's response to the soldiers' capture had been disproportionate
- Pro-Syrian Lebanese President Emile Lahoud vowed to stand by Hezbollah leader Sayyed Hassan Nasrallah
- UN Secretary General Kofi Annan said he expected European nations to contribute troops to a proposed stabilisation force to end the fighting
- The UN warned of a humanitarian disaster as Lebanese flee their homes, with air strikes on roads and bridges hampering efforts to help them
- Shlomo Goldwasser, the father of one of the missing Israeli soldiers, said he hoped all means - legal or illegal - would be used to get his son Ehud back
As Israel launched fresh air strikes and cross-border attacks on Tuesday, six bodies were pulled from the rubble of a home in the Lebanese border village of Aitaroun, and another family was killed in the coastal city of Tyre.
In one attack, 11 Lebanese soldiers were killed at a barracks east of Beirut.
The Lebanese army has been ordered not to respond to the Israeli attacks. But Lebanese soldiers have now died in several strikes, including one on the port of Abdeh on Monday in which nine died.
Fresh volleys of Hezbollah rockets landed on northern Israel on Tuesday. One attack killed an Israeli in the town of Nahariya.
Rockets also hit Haifa, Safed, Acre, Kiryat Shemona, and Gush Halav region near Safed, Israeli officials told AP news agency.
Israeli military officials say more than 700 Hezbollah rockets have now landed in Israel since the crisis began.