Four UN observers die in Israeli air strike as heavy fighting continues in Lebanon

Four United Nations observers were killed last night in an Israeli raid on their post at the border town of Khiam in south Lebanon. The UN secretary general suggested last night that it had been deliberately targeted.

The observers, said by Lebanese officials to have been an Austrian, a Canadian, a Chinese and a Finn, were killed when the post's building and shelter were bombed.

Milos Struger, the spokesman for the United Nations Interim Force in Lebanon (Unifil), the 28-year old-year old peacekeeping mission in Lebanon, said rescue workers had to dig through the rubble but that Israeli fire " continued even during the rescue operation".

In Rome, where he had been discussing the 14-day-old conflict with Condoleezza Rice, the US Secretary of State, and Fouad Siniora, the Lebanese Prime Minister Mr Annan protested at what he called the "apparently deliberate targeting" by the Israel Defence Forces of the post and demanded a full investigation. There was no immediate comment from the IDF.

Israel has long criticised Unifil for being "innefective" and not standing up to Hizbollah. Beside triggering a probable wave of international protest, the deaths of the four observers may complicate further the search for a ceaefire agreement under which a multinational force would take over control of the southern border areas of Lebanon.

Mahmoud Ahmadinejad, the Iranian President, also warned that the conflict between Lebanon and Israel could trigger "a hurricane" of broader fighting in the Middle East. Iran is a major backer of Hizbollah and a sworn enemy of Israel. In his comments, he referred to a proverb that says: " He who raises the wind will get a hurricane." He added: "That proverb fully relates to the Middle East, which is a very volatile region. And it will be a strong hurricane which will strike really hard."

Egypt and Saudi Arabia, facing popular anger over Israel's offensive, toughened their stance yesterday warning the US that Israeli militarism could lead to a wider conflict in the region.

Meanwhile, Da'aa Abbas, 15, became the fourth Arab Israeli to die in the conflict ­ killed in the Galilee village of Maghar as Hizbollah launched 90 to 100 rockets at northern Israel.

Amir Peretz, the Israeli Defence Minister, said Israel will enforce a " security zone" in southern Lebanon until such time as a multinational force moves in to control the Lebanese border area. The remarks by Mr Peretz appeared to set the seal on Israel's conversion to the idea of a Western-led international military deployment to keep Hizbollah guerrillas from threatening Israel, if and when the still slow-moving diplomatic efforts to broker a ceasefire succeed.

Beirut was heavily bombarded from the air yesterday after Israeli military aircraft killed six people in the southern Lebanese city of Nabatiyeh, and Israeli troops sealed off the town of Bint Jbeil, 15 miles farther south, which it regards as a Hizbollah stronghold.

Ms Rice said yesterday, after meeting Ehud Olmert, the Israeli Prime Minister, in Israel that any Lebanon ceasefire would have to be " enduring" as well as urgent, and that the US was seeking a "new Middle East".

Ms Rice, who arrived in Rome last night to meet European and Arab leaders, supposedly to thrash out terms of a putative ceasefire, said there was " no desire" on the part of US officials to come back weeks or months after a ceasefire because, she implied, Hizbollah had again found a way to undermine it.

Her remarks came as Javier Solana, the European Union's foreign affairs envoy, said he would be calling for a "ceasefire process" at the summit, and added that European countries would have to take part. " Without European, without some Europeans, the force will not exist," he said.

There have been suggestions in Israel that such a force, which it would prefer to be under the aegis of Nato, would require 20,000 troops ­ twice as many as the deployment being talked about in Western capitals. While Mr Solana did not say so, France has been seen as a potential contributor.

Mr Solana refrained from saying he would call for an "immediate ceasefire" ­ apparently out of deference to Britain, which has joined the US in refraining from such a demand.

Israeli officials have suggested that the US has informally given licence to Israel to maintain its assault in Lebanon until at least the beginning of next week.

The death of the Arab Israel girl came amid continuing indications from Israeli officers, and troops at the border, of the stiff resistance put up by Hizbollah to the tank and infantry incursions into southern Lebanon over the past few days. Heavy fighting around the village of Maroun ar-Ras cost the lives of seven Israeli soldiers at the end of last week.

Brigadier General Shuki Shachar, the deputy head of the Israeli Defence Forces northern command, said the army had taken the "high positions" around Beit Jbeil to pursue its operations against Hizbollah rather than occupying the town itself after persuading most of its 20,000 civilians to leave. He said the civilians would not be allowed back as long as Hizbollah threatened Israel. Major Eran Carraso, who served in Lebanon before the Israeli withdrawal in 2000, said the effectiveness of Hizbollah forces had notably improved.

A 21-year-old tank commander who had just spent 80 hours in Lebanon and gave only his first name, Erez, said the operation had been very different from his service in the West Bank. But he insisted that Hizbollah fighters were "cowards" because they fired missiles and then went into hiding.

One of the more remarkable sights on the border yesterday was the return of a foot patrol with llamas, which the Israeli army recently decided were especially suitable beasts of burden for operations inside the hilly terrain of southern Lebanon.

The mounting toll

* Number of Lebanese people killed in the two-week conflict: 422, of whom 375 were civilians.

* A further 27 Hizbollah guerrillas have been killed and 20 Lebanese soldiers.

* Number of Israeli dead since the conflict began: 42, of whom 18 were civilians and 24 soldiers.

* Number of Palestinians killed by Israel in the Gaza Strip since the capture of Cpl Gilad Shalit: 121.

* Number of Israeli air strikes on Lebanon yesterday: 100.

* Hizbollah rockets fired yesterday: 80.

* The Israel Defence Force claimed yesterday to have hit 10 Hizbollah buildings.

* That adds up to an estimated $1bn ($600m) in damage to infrastructure.

* Number of Lebanese bridges destroyed: 105

* The number of Israeli bridges destroyed: 0.

* Number of Lebanese ports bombed: 3.

* Estimate of the number of Lebanese people displaced in the fighting: 750,000.

* Lebanon has 2,000 UN troops who have been in the south since 1978.

* The value of arms exported to Israel from the UK in the past 18 months: £25m.

* The number of Britons evacuated from Lebanon by yesterday evening: 2,526.

* Israel's military spending: $9.45bn (in 1995); Lebanon: $540