JERUSALEM — Hezbollah has committed “an act of war” by digging tunnels under Israel’s border with Lebanon, Prime Minister Benjamin Netanyahu said Wednesday, calling on the United Nations to halt what he called a “grave violation” of Israel’s sovereignty.

Speaking at a news conference ahead of a United Nations Security Council discussion about the tunnels, Mr. Netanyahu demanded that Lebanon take action and called on the council to order the United Nations peacekeeping force in southern Lebanon to “deepen its operations.” The Security Council discussion pushed by Israel and the United States and the news conference were both part of a campaign by Mr. Netanyahu’s government to attract international attention to the issue.

For more than two weeks, an Israeli military operation has exposed and blocked tunnels dug by Hezbollah, the Lebanese Shiite militia that is backed by Iran. Israel has portrayed this as part of a broader regional effort to curb Iran’s influence.

“This is not merely an act of aggression. It’s an act of war,” Mr. Netanyahu told reporters at Israel’s Parliament. “It is part of a war plan, I would say,” he added, referring to Hezbollah’s suggestions that its fighters would try to infiltrate Israel in a future conflict.