The Israeli military on Monday said its own artillery fire killed an Israeli civilian a day earlier near the northern border with Lebanon, where its forces are fighting Hezbollah.

After opening an investigation, the military said "the initial findings suggest that the Israeli civilian was killed by IDF artillery fire conducted to support IDF soldiers operating in southern Lebanon".

Israel said it struck "Hezbollah" targets in south Lebanon on Sunday shortly after the military was ordered to destroy bridges allegedly used by the Iran-backed group across the Litani River.

Iran's military threatened on Sunday to completely shut down the strategic Strait of Hormuz if U.S. President Donald Trump acts on threats to target the country's power plants.

U.S. President Donald Trump on Saturday gave Iran 48 hours to reopen the Strait of Hormuz to shipping or face the destruction of its energy infrastructure, as Tehran launched its most destructive attack yet on Israel.

Iran's powerful parliament speaker Mohammad Bagher Ghalibaf threatened on Sunday to irreversibly destroy vital infrastructure across the region if the United States and Israel attacked its own.

Israeli Prime Minister Benjamin Netanyahu vowed on Sunday to pursue senior commanders of Iran's Revolutionary Guards "personally", during a visit to an Israeli town struck by an Iranian missile the previous day.

Iranian missile strikes on two southern Israeli towns wounded more than 100 people on Saturday, medics said, after Israeli air defence systems failed to intercept the projectiles.

Israeli Defense Minister Israel Katz said Sunday that the army had been ordered to destroy more bridges over the Litani river being used by Hezbollah in south Lebanon and to step up the demolition of houses.

"Prime Minister Benjamin Netanyahu and I instructed the IDF (army) to immediately destroy all the bridges over the Litani River that are used for terrorist activity, in order to prevent Hezbollah terrorists and weapons from moving south," Katz said in a statement.

Israel said rocket fire from Lebanon killed one person on Sunday as Hezbollah said it attacked soldiers in northern Israel, the first fatality there in fire from Lebanon since the latest war erupted.

During almost three weeks of war in Lebanon, British-Palestinian doctor Ghassan Abu-Sittah has had no respite, telling AFP he has been working "against the clock" to save children wounded in Israeli bombardment.