Israel's defense establishment has raised its intelligence alert in case Hezbollah decides to exploit its hold on Lebanon to wage an armed conflict south of the Litani River, Army Radio reported on Monday.
Nevertheless, Israeli security officials are downplaying concerns of an imminent direct conflict with the Lebanon-based militant group, the radio said.
Hezbollah guerillas seized west Beirut over the weekend and sectarian clashes have raged across Lebanon between the group and pro-government fighters for six consecutive days.
Heavy fighting broke out in the northern city of Tripoli on Monday, Lebanese security officials said. Officials said machine gun fire and rockets were being used in battles between government supporters and pro-Syrian gunmen. Earlier fighting in Tripoli stopped Sunday morning. But it broke out again Monday after Lebanese troops pulled out from the area.
Lebanese paramedics also said Monday that at least 36 people were killed in clashes in a mountainous region Beirut, bringing the death toll to 81 since the fighting began on May 7.
The defense establishment is particularly concerned about Hezbollah's relationship with Iran and the possibility that it is upgrading its rocket arsenal with Tehran's help.
On Sunday, former IDF chief of staff Amnon Lipkin-Shahak said Hezbollah's persistent attempts to take over Lebanon could eventually benefit Israel in its struggle against the militant group.
"If an armed conflict erupts it will be simpler to strike Lebanon when Hezbollah is the legitimate ruler," Shahak told the Army Radio.
Earlier on Sunday, Israel's Vice Premier Haim Ramon told cabinet members that Lebanon must be viewed as a "Hezbollah state," after the Shiite guerilla group seized control over the western part of the Lebanese capital over the weekend.
"Lebanon has no government. It is a fiction, there is only Hezbollah," Ramon said during the weekly cabinet meeting. "Hezbollah is directly responsible for everything that happens [in Lebanon], and the organization completely controls the state."
Later in the cabinet meeting, Minister Ami Ayalon called for an emergency meeting of the political-security cabinet to discuss the ongoing crisis in Lebanon and Gaza.
Ayalon said that "the critical situation in the north" and the impending lull in the fighting in Gaza require a special session.
Also during the meeting, Military Intelligence Chief Amos Yadlin said Lebanon had been embroiled in a political crisis since former Lebanese president Emile Lahoud completed his term and stepped down.
Referring to Lebanon's inability to appoint a new president since then, Yadlin said "there is a consensus regarding the identity of a president, and that is Lebanese army commander, General Michel Suleiman, but the objective of the extreme camp goes far beyond the selection of a president. They want to restore the balance of power in Lebanon to what it was before the anti-Syrian revolution."
According to Yadlin, "in the beginning, Hezbollah tried to do it in democratic ways, and later via non-violent demonstrations, and they failed, and that is why they advanced to a move involving a military force."
Minister of Religious Services Yitzhak Cohen (Shas) said that "Israel must immediately ask the [United Nations] Security Council to hold renewed discussions over resolution 1701." The minister was referring to the resolution that ended the 34-day conflict between Israel and Hezbollah in 2006, maintaining a fragile cease-fire.
According to Cohen "the Lebanese army proved to be a doormat, stepped on by Hezbollah."
Prime Minister Ehud Olmert said that Israel was following the violence in Lebanon closely, but would refrain from intervening.
Deputy Defense Minister Matan Vilnai told Army Radio Sunday that Israel was prepared for the possibility that the situation in Lebanon will deteriorate into another civil war.
Vilnai also said the current sectarian fighting could end with a Hezbollah takeover of the government.
"We need to keep our eyes peeled and be especially sensitive regarding all that is happening there," Vilnai told Army Radio.
"We shouldn't get involved. We need to watch and should follow this very closely even when we are dealing with other fronts," he said, referring to continued fighting against the Iranian-backed Hamas militant group in the Gaza Strip. Hamas has controlled Gaza since last June.
"Israel is especially concerned about the situation in Lebanon in light of the Hamas' control of Gaza," Vilnai said. "Hamas and Hezbollah, as Iranian proxies, are mutually dependent," he said. Gaza is located on Israel's southwestern flank, while Lebanon sits on Israel's northern border.
Cabinet Minister Meir Sheetrit said Israel should not yet take any action, but warned that things could change if Hezbollah takes over Lebanon.
"I think it's very dangerous, the [possible] situation in which Iran is in fact sitting on our border, and controlling Lebanon," Sheetrit said. "It's really dangerous in the long term because now its plain to everyone that ... Hezbollah is just the long arm of Iran and that's the way we should relate to it."
For the time being, Jerusalem has decided not to issue any official comment on the confrontations between Hezbollah and the Beirut government. But various officials have expressed concern over the escalation and the possible implications for Israel's northern border.
Lebanon: IAF flies over south of country
Meanwhile Sunday, a Lebanese security official reported that Israel Air Force warplanes violated Lebanon's airspace and flew over the southern part of the country.
"More than four Israeli jets flew over areas near the port city of Tyre," the official said.
IAF jets regularly overfly Lebanon in violation of UN Security Council Resolution 1701. The United Nations has called on Israel to stop doing so. The organization says the overflights undermine the credibility of UN peacekeepers stationed in southern Lebanon to observe a fragile ceasefire in the area.