"We are ready to act and have completed our preparations," Israeli Prime Minister Ariel Sharon warned. But in the evening, several Katyusha rockets were fired from the western Beka'a valley into the northern part of the Israeli-occupied Shebaa Farms. Hezbollah said it had "no information" regarding the attack.

In a telephone conversation with UN Secretary-General Kofi Annan, Lahoud called on the UN to use its resources to halt "Israeli aggression" as "force achieves nothing." Annan telephoned Lahoud and Syrian President Bashar Assad following Israeli warnings that the spate of attacks along Lebanon's southern border since Saturday could have "alarming consequences." In a meeting with Lahoud, US Ambassador Vincent Battle said the US was "concerned" at the "Palestinian and Hezbollah activities in the Shebaa Farms." "We have urged the Lebanese government to do all it can to halt the breaches and attacks across the Blue Line to avoid any escalation of any kind," he said, referring to the UN-delineated line marking Israel's troop withdrawal. Foreign Minister Mahmoud Hammoud also met with Battle, as well as with British Ambassador Richard Kinchen, who called for "maximum restraint." Hammoud said that "Lebanon has no intention of opening a new front on its border."

But tensions remained critically high yesterday after the Israeli Government said that it would no longer tolerate attacks along its frontier with Lebanon.

"We are ready and prepared for all actions that we will take as required. We do not intend that the situation here will return to what it was," Sharon told reporters during a visit to the headquarters of the Israeli Army's northern command. Sharon's visit came a day after an Israeli soldier was wounded when Hezbollah guerrillas pounded several outposts in the Shebaa Farms. A Katyusha rocket and 116 mortar rounds were fired in the space of about two-and-a-half hours.

The Katyusha salvo occurred early in the evening and targeted the Israeli listening post at the northern tip of the Shebaa Farms. The rockets were apparently fired from Marj Zahour, 12 kilometers away. Marj Zahour was home to 400 Hamas men for several months in 1994 after Israel rounded them up in the Occupied Territories and expelled them north of the occupation zone. There was no customary Israeli artillery reprisal to the attack, which Lebanese security sources regarded as an ominous sign.

Earlier, UNIFIL's commander, Major General Lalit Mohan Tewari, said that he was "guardedly optimistic" that the situation would calm down.

Tewari, who has met in the past two days with Lahoud, Premier Rafik Hariri and Army Commander General Michel Suleiman, said UNIFIL patrols had increased due to the escalation. He added that the stepped-up patrols may have saved the lives of four officers of the UN Truce Supervision Organization who were badly beaten by Hezbollah fighters yesterday in Upper Halta at the foot of the Shebaa Farms.

The UNTSO officers — an Irishman, a Frenchman and two Norwegians — were barred from passing through the village by about eight armed Hezbollah fighters. An argument broke out and the four UN officers were thrown to the ground and assaulted. An Indian UNIFIL patrol arrived on the scene and in the ensuing scuffle two peacekeepers were lightly injured. No shots were fired. "I think possibly ... the Indian patrol saved the life of these military observers," Tewari said.

The Irish officer suffered a fractured skull and was rushed to Rambam Hospital in Haifa. Two other officers had broken arms and were treated at the UNIFIL hospital in Naqoura. The Indian soldiers were treated at their headquarters in Ibl as-Saqi.

Annan "strongly condemned" the incident. Hezbollah offered "profuse apologies," a UNIFIL officer said. There have been numerous reports of UN personnel being harassed by Hezbollah fighters since Hezbollah consolidated its presence in the border area following Israel's withdrawal in May 2000. But this incident was the most serious and could have adverse repercussions on relations between Hezbollah and UN peacekeepers.