A statement issued on Wednesday said Ehud Olmert, the Israeli prime minister, had been informed by Condoleezza Rice, the US secretary of state, and Kofi Annan, the UN chief, that "international forces are ready to take over control posts over the sea ports and airports of Lebanon".
"Thus it was was agreed that tomorrow at 6pm (1500 GMT), Israel will leave the control positions over the ports in conjunction with the entry of the international forces," the statement said.
Israel said German experts were to arrive at Beirut airport on Wednesday and German naval forces were also expected to arrive within two weeks to deploy on the Lebanese coast.
Until then, Italian, French, British and Greek troops would man the control posts.
Fawzi Salloukh, the Lebanese foreign minister, had earlier said that his country would break Israel's blockade "with all our might" if it was not lifted in a 48-hour timeframe indicated by the UN secretary-general.
said: "We will wait for the 48 hours given by Kofi Annan, and if the situation is resolved, we will thank him. If it is not, the Lebanese government will take the necessary measures and we will break the blockade with all our might."
"... the Lebanese government will take the necessary measures and we will break the blockade with all our might"
Lebanese foreign minister
Annan had told reporters in the Egyptian port city of Alexandria on Tuesday that he hoped for "positive" news within 48 hours in his efforts to persuade Israel to lift the blockade imposed on Lebanon.
Fouad Siniora, the Lebanese prime minister, had said that if the blockade went on for another 20 days, the economic losses would equal the nearly $1 billion in aid promised by international donors to help the country get back to its feet after the war.
In an earlier sign that the embargo could be crumbling, British Airways-linked British Mediterranean Airways had said on Wednesday that it was resuming direct flights to Beirut after the British government had given assurances that it would be safe to do so.
Lebanon's Middle East Airlines and Royal Jordanian began flying regularly into the capital last month, but have complied with Israel's insistence that all such flights go via Amman. Qatar Airways resumed direct flights to Beirut on Monday.
Annan is due to report to the Security Council soon on progress towards implementing UN resolution 1701 that led to the Israeli-Hezbollah truce on August 14.