“I can’t fight in the Israeli army because I’m Arab,” the 19-year-old with gelled hair and flash trainers said. “But I’d go down to the hospital and help out with the injured. We are all in this together, Jews and Arabs. The rockets make no distinction.”

But along the shuttered and nearly deserted street in the city’s Arab neighbourhood it was clear that many had heeded the warning, grabbed some belongings and headed out of the city to safer areas in the south of the country.

“In the street where I live at least seven families left the morning after Nasrallah appeared on TV,” Assad Khouria, 42, a storekeeper, said. “When he talked specifically about Haifa, that was the straw that broke the camel’s back.” The father of three’s daily takings have dwindled by two thirds. But despite the terror of his children and the death of his aunt when a missile struck her home on Sunday, he is staying.

The sirens wail across Haifa at terrifying intervals, sending Arab residents scurrying for makeshift cover, though few of the city’s older houses have bomb shelters.

A rocket crashed into a suburb within hours of Sheikh Nasrallah’s threat, which was coupled with a plea that he did not want further Arab casualties.

“I have a special message to the Arabs of Haifa, to our martyrs and to your wounded,” he said in a televised address. “I call on you to leave this city. I hope you do this . . . Please leave so we don’t shed your blood, which is our blood.”

The ultimatum turned the trickle of those fleeing into a flood, leaving only those too stubborn or too poor to find shelter outside Haifa, whose population of 300,000 includes 35,000 Arabs. With Israel’s Arab community — 20 per cent of the population — clustered in the north, it has already suffered disproportionately. Of 38 civilians killed, 17 are Arabs. Fouad Mayo, 47, almost became another statistic. His son, aged 7, saw a streak in the sky a split second before a rocket hit the house opposite, severely injuring two of the occupants and leaving the house a pile of rubble.

The warning was just long enough for him to grab his wife and three children and dive under some mattresses in a back room to shield them from the flying glass and debris.

“I sent my wife and children to a hotel in Tel Aviv because they were totally traumatised,” he said, as builders replaced his windows. “But I’ll never leave even though I know it’s got more dangerous.”

Khalifi Ashadi, 33, an Arab Christian painter whose five children vomit with terror every time an alert sounds or a rocket explodes, said: “Nasrallah is a terrorist. He doesn’t care who gets killed in this. It doesn’t matter to him whether it’s Arabs or children. The last thing he wants is peace.”

Mr Ashadi is rare, as despite the death and destruction, Haifa’s Arabs reveal a split loyalty and few are willing to condemn the Hezbollah leader.

“I don’t back Hassan Nasrallah,” said Diab Mutlak, 52, a senior doctor at Rambam Hospital in Haifa. “But I don’t support what the Israelis are doing in Lebanon either. Nasrallah doesn’t care who he kills, but I don’t think the Israelis in Lebanon care either. The problem is not Nasrallah, but the quarrel between Arabs and Jews.”

Times Recommends

• Air crash: ‘Everything is burnt. It is the closest thing to Hell’
• The true story of a passionate Korean 'spy'
• I shot Lennon in the back, Chapman tells parole board