The Israeli military announced it was expanding its ground campaign against Hezbollah in Lebanon, warning of a lengthy operation, after Beirut condemned what it called Israel’s flagrant violations of Lebanese sovereignty.

Israeli forces were ordered earlier Sunday to destroy bridges they said were used by the Iran-backed group Hezbollah to cross the Litani River, and Lebanese official media reported Israeli raids in several areas of the south.

An AFP correspondent saw smoke billowing from a bridge that was hit outside the city of Tyre. “The operation against the Hezbollah terrorist organisation has only begun… This is a prolonged operation,” Lieutenant General Eyal Zamir said in a statement.

“We are now preparing to advance the targeted ground operations and strikes according to an organised plan,” he added.

Lebanese President Joseph Aoun had earlier warned that the bridge attacks “represent a dangerous escalation and flagrant violation of Lebanon’s sovereignty, and are considered a prelude to a ground invasion.”

Lebanon was pulled into the Middle East war when Hezbollah began firing rockets into Israel on March 2 to avenge the killing of Iran’s supreme leader, Ayatollah Ali Khamenei, in an Israeli-US strike.

Israel has sent troops into Lebanon and carried out extensive airstrikes, while Hezbollah has launched rocket barrages.

Israel’s military said Sunday it began “a wide wave of strikes” against Hezbollah infrastructure in southern Lebanon.

According to Lebanon’s state-run National News Agency (NNA), three strikes on the bridge near Tyre “caused extensive damage, rendering it unusable”. It was later reported that a fourth strike occurred.

Aoun “condemned Israel’s targeting and destruction of infrastructure and vital facilities in southern Lebanon, particularly the Qasmiyeh bridge over the Litani River and other bridges”.

“Targeting bridges over the Litani River… is an attempt to sever the geographical link between the area south of the Litani and the rest of Lebanon’s territory,” he added.

The NNA also reported that Israeli forces were “blowing up several houses in the town of Taybeh” near the border with Israel.

Earlier Sunday, Israel said rocket fire from Lebanon killed a civilian, but later announced it was investigating whether “the incident involved fire originating from IDF soldiers”.