Israel said on Thursday that its ceasefire with Hezbollah was breached hours after Lebanese security sources said Israeli tanks attacked six areas of southern Lebanon, calling into question a truce reached after more than a year of fighting.

A cease-fire between Israel and Hezbollah brokered by the U.S. and France took effect in Lebanon early Wednesday, raising hopes of ending more than a year of cross-border strikes and a full-scale war that has killed thousands.