Israeli warplanes on Saturday struck the Lebanese main crossing point of Masnaa near the border with Syria, closing the passageway, security sources said.
One person was wounded when three missiles slammed into the last customs building at the crossing point, digging craters in the middle of the road, they said.
The closure left one route through northern Lebanon to Syria as the only relatively safe passage out of the country. The airport has been closed since its runways were blasted by an Israeli air strike on July 13.
Israeli warplanes had attacked the same border area on July 15, days after Israel launched a massive offensive on Lebanon following the capture of two of its soldiers by the Lebanese Shiite militant group Hezbollah.
The air raids on Saturday came after Hezbollah chief Hassan Nasrallah vowed to strike cities in central Israel, declaring that the Jewish state had failed to win any military victory after days of bloody clashes with his guerrillas.
It also followed an announcement by an explosives specialist with the Israeli police that the "unknown" missile fired by the pro-Syrian Hezbollah at the Israeli town of Afula on Friday was Syrian-made.
Port authorities, meanwhile, said no evacuation boat was scheduled to leave from Beirut on Sunday for the first time since the exodus by sea of foreign nationals was launched on July 17 by an Italian destroyer.
Tens of thousands of foreigners have since been evacuated on a daily basis by a flotilla of civilian and military ships laid on by their home countries, while smaller numbers have been helicoptered to Cyprus.
