TYRE, Lebanon — Israeli planes targeted bridges in southern and eastern Lebanon in new airstrikes Saturday, destroying one in a resort area on the Syrian border, as U.S. Secretary of State Condoleezza Rice was returning to the region to try to broker peace.

Also on Saturday, Israel rejected a request by the U.N. for a three-day cease-fire in Lebanon to deliver humanitarian supplies and allow civilians to leave the war zone.

Avi Pazner, a government spokesman, said Israel already has opened safe corridors across Lebanon for such shipments and that Hezbollah guerrillas were blocking them to create a humanitarian crisis.

As the fighting continued, Rice was bringing a package of proposals to Lebanese and Israeli leaders aimed at ending the fighting. She plans to meet first with Israeli Prime Minister Ehud Olmert in Jerusalem on Saturday night, said Mark Regev, spokesman for Israel's Foreign Ministry.

Rice's peace plan seeks an international agreement on a U.N.-mandated multinational force that can provide stability in the region, according to a U.S. official. It also proposes disarming Hezbollah and integrating the guerrilla force into the Lebanese army, a commitment to resolve the status of a piece of land held by Israel and claimed by Lebanon, a no-go buffer zone be set up in southern Lebanon, Hezbollah returning Israeli prisoners, and the creation of an international reconstruction plan for Lebanon.

The United States, backed by Britain, has adopted a diplomatic stance not embraced by most allies, insisting that any cease-fire must come with conditions to address long-standing regional disputes. Many Europeans and Arab countries are increasing the pressure for an immediate cease-fire first, followed by a plan to tackle the more complicated issues of curbing Hezbollah's guerrillas.

A groundswell of support has grown in the Arab world for Hezbollah, which many regional governments initially criticized for provoking the conflict.