Thousands of Lebanese and foreign nationals were fleeing Hezbollah-controlled southern areas tonight after a day of intense Israeli air strikes in which at least 43 people were killed, pushing the death toll from the six-day military offensive to over 200.

Hopes that the onslaught might soon come to an end appeared misplaced when Ehud Olmert, the Israeli Prime Minister, made a hard-hitting speech to the Knesset tonight, in which he vowed to "hunt down every single terrorist" in Israel's campaign against both Hamas and Hezbollah.

"Are are we to throw up our hands and give in to these threats from the axis of evil or are we to stand fast and keep a cool head? Our response is known to every single citizen," declared Mr Olmert, who blamed Syria and Iran for fomenting the violence. "When missiles rain down on our cities our response will be to wage war with even greater determination."

As Lebanese living near the Israeli border headed to the relative safety of Beirut, foreign countries prepared for a mass evacuation of their nationals that one British minister said might be "the biggest evacuation since Dunkirk".

Dominique de Villepin, the French Prime Minister, flew into Beirut tonight to express France's solidarity with Lebanon, which it governed under League of Nations mandate between the two world wars and with which it retains close ties.

Israeli forces entered southern Lebanon overnight to attack Hezbollah bases, the first use of ground troops since the abduction of two Israeli soldiers prompted the violence. But an Israeli army spokesman described it as a "very small incursion" to destroy some Hezbollah positions across the border.

The crisis dominated discussions at the G8 summit in St Petersburg, where Tony Blair led calls for the deployment of an international stabilisation force in southern Lebanon, although there is no suggestion that such a force could be sent in before a cessation of hostilities. Israel rejected the move as premature.

After a meeting with Kofi Annan, the UN Secretary-General, on the fringes of the summit, Mr Blair emerged to tell reporters: "The very obvious question is why don’t we just say to everyone ‘You have got to stop and stop right now’?

"The answer to that is, it isn’t going to stop now unless we create the conditions in which there can be such a cessation. And for that to happen in the north, between Lebanon and Israel, the only way, in my view, we are going to get a cessation of hostilities is if we have the deployment of an international force into that area."

Several thunderous blasts echoed over Beirut at dawn today and black smoke rose from a blazing fuel storage depot in the Christian suburb of Dora. Civilian installations, petrol stations and factories elsewhere were also hit.

Forty-three Lebanese were reported killed in air strikes around the country and a further ten bodies, victims of an air strike in the city of Tyre yesterday, were found. Officials said that 192 civilians and 12 soldiers have been killed since last Wednesday. One the Israeli side, a total of 12 civilians have been killed in the barrage of Hezbollah rocket fire which is penetrating more than 40 miles inside Israeli territory.

One rocket today caused the collapse of a three-storey building in Haifa, Israel's third-largest city, although it was not clear if anyone was killed in the attack. The rocket attacks forced authorities to close the Haifa port.

Cyprus geared up for an influx of thousands of evacuees, as air and sea lifts were launched to ferry thousands of foreign nationals out of conflict-wracked Lebanon. A French government-chartered cruise ship, which can carry 1,300 passengers, arrived in Beirut from the Cypriot port of Limassol to pick up Europeans desperate to escape Israel’s aerial onslaught.

Around 40 British citizens, mostly women, children and the elderly, were evacuated from Beirut this morning by an RAF Chinook helicopter. Royal Navy warships are also steaming towards the Lebanese coast for a rescue operation, but are not expected to arrive until Wednesday.

In a statement to the Commons, Kim Howells, the Foreign Office Minister, said that there were about 12,000 British nationals in Lebanon and a further 10,000 with dual nationality. Britain also had some agreements with other Commonwealth states.

"We could have some responsibilities there too," Mr Howells said. "The figures become very large when we take those numbers into account. If these numbers have to be evacuated, it becomes the biggest evacuation since Dunkirk."

The minister raised cheers, however, when he said that on the question of a peace-keeping force going in "we do not envisage any British soldiers or service personnel being part of that". He added: "This is a situation which affects the whole of the world. There are many nations that are going to put their armed forces where their rhetoric has been up until now."

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