TWO loud bangs echo through the United Nations peacekeeping headquarters in the coastal village of Naqoura and twin trails of white smoke are seen curving in a southward direction as Hezbollah’s latest salvo of rockets streaks across the border into Israel.

The Israeli military has saturation air coverage over southern Lebanon with missile-firing reconnaissance drones, Apache helicopter gunships and F16 fighter-bombers. It is attacking its Hezbollah enemy with multiple airstrikes and heavy artillery bombardments from land and sea as well as raids by Israeli special forces units.

Yet Hezbollah squads are still firing dozens of rockets a day into Israel from locations lying just a few hundred yards from the border and within full view of the Israeli military.

One such position lies between the villages of Naqoura and Alma al-Shaab. The rocky, uninhabited hillside and deep ravine of 12 square miles is covered in a dense undergrowth of juniper bushes and scrub oak where Hezbollah over the past three years has established an unseen, but clearly formidable, military infrastructure of weapons depots, tunnels and bunkers.

For almost a month the Lebanese guerrillas operating on the hillside have withstood huge Israeli artillery barrages and air raids that have burned vast tracts of the hillside.

Even seasoned UN observers, whose headquarters is at the foot of the hill, are baffled at how the guerrillas have managed to survive the onslaught and keep up a steady rate of rocket fire. “We simply have no idea how they have been able to fire rockets for so long from more or less the same location and the Israelis have not been able to stop them,” said a senior officer for United Nations Interim Force in Lebanon.

A narrow lane winds up the hill from Naqoura and ends at the border fence at Labboune, a long-abandoned farm where the UN has a communications position. Labboune was a popular tourist spot because of its sweeping views over the Western Galilee coastline but Hezbollah fighters sealed off the road three years ago and the area became a military zone.

Military observers believe that in the following months Hezbollah built a series of defences and fortifications in expectation of a showdown with Israel. Uniformed and armed fighters could occasionally be spotted creeping through the dense bush on reconnaissance patrols along the border.

“They have amassed huge stockpiles of rockets in the area,” General Alain Pellegrini, Unifil’s commander, told The Times in an interview at his office in Naqoura. “I think the Israelis were hoping they would have had a faster success against Hezbollah by now.”

Israeli forces are operating along almost the entire length of the 70-mile border, but so far they have been engaged in a series of probes and small incursions rather than a concerted push to seize and hold Lebanese territory.

In 1982, Israeli armoured columns smashed through Palestinian lines to reach and encircle Beirut in nine days. But after nearly four weeks of fighting, Israeli forces are no more than a few miles into Lebanon, establishing toeholds along the border and a few forward positions and meeting stubborn Hezbolah resistance.

The battle over the Naqoura hillside appears to be drawing to a climax. Last week, Israeli forces and tanks crossed the border east of Alma al-Shaab and then inched their way in a northwesterly direction to reach the Mediterranean coast, in effect cutting off the dug-in Hezbollah squads to the south.

Before dawn on Sunday, helicopter-borne Israeli commandos landed at the clifftop village of Biyada, which commands views over the Mediterranean and much of the Lebanese coast to the north. Heavy fighting continued unabated yesterday as the Israeli troops consolidated their position, while Hezbollah fired more Katyusha rockets from the hillside outside Naqoura. But the Lebanese guerrillas, who are thought to be acting in small autonomous groups, are trapped between the sea, the border with Israel and the Israeli troops to the north. That leaves the Hezbollah fighters with the choice of using the rugged terrain to try to slip through Israeli lines or to stay and fight to the last man.

Most of southern Lebanon is now isolated after Israeli jets bombed a causeway across the Litani river yesterday morning that had been the only lifeline connecting the south to the rest of the country. The bridges across the Litani were blown up in the first two days of the war.

The UN has been pressing the Israeli authorities to allow a military bridge to be built by Unifil’s Chinese engineering battalion across the river on the coastal road, saying that it was vital for the flow of humanitarian aid to the south. Israel said yesterday that it would bomb any bridge.

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