The exchange sparked concern about whether the ceasefire would hold, days after Israel relaunched war with another Iran-backed militant group, Hamas, in Gaza.

Israeli artillery and airstrikes hit south Lebanon on Saturday after Israel said it had intercepted rockets fired from across the border, endangering a shaky truce that ended a year-long war between Israel and the Lebanese armed group Hezbollah.

The Israeli air force has carried out airstrikes on what it said were Hezbollah targets in southern Lebanon after rockets were fired over the border, a significant flare-up in tensions after a ceasefire brought uneasy calm to the region.