The Israeli air force says it struck Hezbollah targets in southern Lebanon in response to cross-border rocket fire in the most significant flare-up of tensions since a ceasefire brought uneasy calm to the region.

Israel struck Lebanon on Saturday in retaliation for rockets targeting Israel, killing two, including a child, in the heaviest exchange of fire since the ceasefire with the Lebanese militant group Hezbollah.

The cross-border exchange came less than a week after Israel ended a separate ceasefire with Hamas in Gaza by launching a series of air strikes that killed hundreds of Palestinians, according to local officials, and resumed ground operations in the shattered enclave.