Israel's prime minister on Thursday asked the international community to impose additional sanctions on Hezbollah and condemn the Lebanese militant group in response to the discovery of tunnels stretching from southern Lebanon into northern Israel.

Israel this week launched an open-ended operation meant to expose and thwart what it says are tunnels built by Hezbollah aimed at infiltrating Israel. The two sides are bitter enemies and fought an inconclusive monthlong war in 2006.

Benjamin Netanyahu toured the operation's area with a group of ambassadors Thursday.

"I told the ambassadors that they need to unequivocally condemn this aggression against us by Iran, by Hezbollah and by Hamas, and of course, to also strengthen the sanctions against these elements," Netanyahu said.

Netanyahu also said he will demand the U.N. Security Council discuss the matter.

He said that at the end of the operation, the tunnels "will no longer exist and will no longer be effective."

Lt. Col. Jonathan Conricus, a military spokesman, told reporters Thursday that the army is now operating in three areas where tunnels have been discovered.

"We are aware of additional tunnels," he said.

He said that Israel's northern commander, Maj. Gen. Yoel Strik, on Thursday gave the head of the U.N.'s peacekeeping force in Lebanon a tour of a tunnel that entered Israel.

Strik also presented UNIFIL a map with the location of a second tunnel, along with houses in Lebanon that Israel says are connected to the tunnel. He said Israel demanded that UNIFIL investigate and "neutralize" the shaft of the tunnel.

In Lebanon, the LBC TV posted an audio message that it said some residents of the border village of Kfar Fila received on their cellphones Thursday warning them to stay away from tunnels.

"Hezbollah is putting your lives in danger because of digging tunnels," said the Arabic audio message, which appeared to have been sent by Israel. "These tunnels could explode. Anyone who is close to the tunnels is putting his or her life in danger."

There was no immediate response from the peacekeeping mission.