The military did not reveal the exact location of the tunnel but said it "does not pose an imminent threat".

"Explosive devices have been placed inside the tunnel by the IDF (Israel Defence Forces)," it said in a statement.

The army announced an operation on December 4 dubbed "Northern Shield" to destroy tunnels it said were dug under the border by the Shiite militant group Hezbollah.

"The Lebanese government is held accountable for the attack tunnels dug from Lebanese territory," the military statement said.

"IDF troops will continue to operate in accordance with the approved plan to locate and expose the Hezbollah terror organisation's attack tunnels."

Israel fought a war against Iran-backed Hezbollah in 2006 that was halted by a UN-brokered truce.

Hezbollah is the only group in Lebanon not to have disarmed after the country's 1975-1990 civil war.

Italy's far-right Interior Minister Matteo Salvini, who arrived in Israel on Tuesday, said on Twitter that he was flying by helicopter to see for himself the tunnels built by "Islamic extremists".