It's 8pm on Monday evening and the Aseli family is in full emergency mode. The power has just gone down in their apartment – for the second time that day – blacking out the lights and the electric heater.

Abed al Aseli, father of the household, rises to light a lamp powered by cooking gas while one of his sons moves in a swift, practised way towards the bed of Maher, 12, in what is literally a life-or-death mission. Maher, paralysed from the neck down for the past six and a half years, normally relies on an electric respirator to breathe. When there is no power, the only alternative, however long the outage lasts, is to maintain his breathing manually with an Ambo hand pump.

Which is why, since last week's cut in fuel supplies to Gaza's power station, Mr al Aseli has recruited his five teenage nephews and nieces to help him, his wife, Alia, and their four other sons and two daughters, aged between eight and 21, working in rotation throughout the night, if necessary, with the nerve-racking, exhausting, task of keeping Maher alive.

Mr al Aseli says this is stressful for the whole family, and that his wife has to spend a disproportionate amount of time caring for Maher in what the family has made, in effect, into a home intensive care unit. "It is very difficult," he says. "If the power goes out at 1am, I have to shout and immediately wake up the kids."

The tragedy which first put Maher into this state had nothing to do with the Israeli-Palestinian conflict. As Mrs al Aseli explains, when Maher was five and a half years old, he was driven by his father to a local supermarket. Mr Maher left his son in the car while he nipped into the store, but as he started to make his way back, he saw in horror that Maher had managed to get out of the car and was crossing the road towards him. Mr Maher shouted at him to stop where he was but Maher was run down close to the family car by a fast-moving taxi whose driver failed to see him. Maher's spinal cord was injured between the second and third vertebrae, leaving him quadriplegic.

He was eventually allowed home – with regular visits from a nurse and doctor – on condition the family used their $36,000 insurance payment to provide everything needed for his home care, including everything from the respirator; suction equipment (also electrical but luckily capable of being run on batteries for 12 hours) for keeping Maher's lungs clear; a medical bed; regular supplies of sterilised tubing and surgical gloves. And, of course, a hand pump for when power is not available.

The reason Maher's case is under discussion now is that it was jointly cited last Sunday in the Israeli Supreme Court – complete with an affidavit from Mr al Aseli – by two Israeli human-rights organisations: Gisha and Physicians for Human Rights.

The two groups were among ten petitioning the court against what they described as the "punitive" cuts in fuel Israel had already imposed – and the planned cuts in electricity directly provided to Gaza – in response to the continued firing of Qassam rockets by Gaza militants, rockets which have been inflicting misery on the Israeli border town of Sderot and other communities in the western Negev.

They were seeking to illustrate that it is impossible to make such cuts without humanitarian cost and that the response constituted what the petitioners insisted was "collective punishment" of Gaza's 1.5 million population.

In the affidavit submitted to the court on Sunday, Mr al Aseli testified to the "terrible anxiety" suffered by the family "especially at night" and said the problem was compounded by the fact that Maher's condition meant he also needed to be kept warm on cold winter nights. With the loving and vigilant family he has, Maher is not going to die. His uncle Mahmoud, a doctor, says that even with only 75 per cent of his respiratory muscles totally dysfunctional, Maher could probably manage – in extremis and with difficulty – to breathe alone for about an hour.

And there is some help from a generator belonging to a nearby health centre, though that only normally operates between 8am and 8pm (apart from interruptions when it breaks down or runs out of diesel) between Sunday and Thursday, shutting down at weekends.

But the strain of looking after his son during the lengthy periods – often around eight hours – that it has been off in recent days is etched on Mr al Aseli's face. When Gaza's power station was put out of action by an Israeli missile strike in the summer of 2006, after the abduction by militants of the Israeli corporal Gilad Shalit, Mr al Aseli bought a large generator for $8,000, which guaranteed 24-hour power for Maher's ventilator. But last year, with power more or less back to normal, and the combination of crossing closures and the international embargo on the Hamas-led administration elected in 2006 hitting his business hard, he sold it. "I didn't need the generator and I did need the money," he explains.

In better times, Mr al Aseli ran a reasonably successful import-export business, buying and selling curtain fabrics with his brother. But he says that since the total closure of the Karni crossing after Hamas's enforced takeover of Gaza in June following the bloody infighting with Fatah, his business has ground to a halt. This is both, he says, because he cannot import the cloth he would need and because few customers can afford new curtains.

As a result, he cannot afford to buy, let alone maintain and supply with the diesel it would consume, a $4,000 generator of the minimum wattage of six to seven kilowatts he would need. He already needs to find such a sum for Maher's medical care and the equipment – including oxygen cylinders – he regularly needs to replenish. While insurance covered the initial outlay, he is still having to pay back the $18,000 he borrowed for the replacement ventilator he needed when the first one wore out.

A generator is beyond him, let alone the massive resources he and his brother, Dr Mahmoud, say the family would need to buy Maher the five-star treatment they would like to see him receive in a hospital in Israel or in Europe. Last night, the local health centre generator shut down at 7pm and the family was back to hand-pumping in an increasingly chilly and darkened apartment an hour earlier than usual.

When you put it to Mr al Aseli that this is the price Gaza's residents are paying for daily barrages of Qassams, which target Israeli civilians and are certainly a violation of international humanitarian law, he becomes animated for the first and last time. "Are all the people in Gaza firing Qassams? Perhaps there are 100 or 200 people firing Qassams. And there are one and a half million people in Gaza. We are not all launching Qassams. Is Maher launching Qassams?"

This goes, of course, to the heart of the argument between Israel and the humanitarian agencies over the cuts in fuel – both to the power station and for use in generators – Israel has imposed since declaring Gaza a "hostile entity" in the autumn. Almost every detail is disputed between the sides. But it is agreed that, after the total ban on fuel and other humanitarian supplies which ended with the closure of Gaza's power station at the beginning of last week, Israel has committed itself to resupplying the power station with about 2.2 million litres of industrial diesel a a week.

Gisha says the power station needs more like 3.5m litres to work to capacity of 80 mega watts as opposed to the current 55. And that Gaza therefore has a 20 per cent power deficit, leaving large parts of Gaza city without power for hours at night. With Israel supplying around 120 mw of Gaza's power, Gisha's hope is that rotating cuts will now be limited to 4-8 hours.

Shlomo Dror, a spokesman for the Ministry of Defence, lists the many unpalatable alternatives which might succeed in reducing the rocket fire which, he says, his minister, Ehud Barak, has sought to stave off by adopting a policy of what he insists are very limited reductions in fuel: a full-scale military operation which could cost "many Palestinian and Israeli lives", the use of artillery or other means – with resultant civilian casualties – to hit back at rocket launchers operating in populated areas; the escalation of targeted assassinations to include not only top commanders but the political leadership of Hamas "which we don't like because we don't know where it would lead us".

He adds that the main purpose is to "send a message that the Palestinians can't go on launching the Qassams; they have to stop them." He adds, moreover, that the policy seems so far to have worked; Qassam launches are down, if not eliminated, he suggests, because in order to maximise the propaganda effect of the power cuts, Hamas has to limit the rocket launches.

Mr Dror continues to question not only Gisha's figures but whether it was really necessary to shut down the power station last week. All that can be said is that while Hamas no doubt helped subsequently to milk the impact of the closure, non-political senior engineers at the power station said Hamas urged them to keep the power station open longer than they wanted. The most respected senior UN officials in Gaza are also adamant that it was necessary.

To Mr Dror's indication that the EU had not asked to fund more than the 2.2m litres a week currently supplied, a senior EU official managing the programme retorted last night: "If we could pay for more, we would. The figure was one unilaterally decided by the government of Israel."

To Mr Dror's further contention that after the June 2006 bombing, the power station was shut down for eight months "without talk of a humanitarian crisis", Gisha points out that it did indeed create severe hardship, but that in winter, with – to take a single example – only 40 out of Gaza's 130 water wells having their own generators – the impact is inevitably much worse.

According to Sari Bashi, Gisha's director: "There is no rational relationship between stopping the Qassams and causing power outages in hospitals. The residents of Sderot need for the Qassams to stop rockets threatening their children. They don't need the children of Gaza to suffer too. International law forbids making civilians suffer in order to pressure militants.

"In the past seven months, Gaza has been suffering from severe spare-part shortages, making it extremely difficult to operate generators or properly maintain the system. There is a 20 per cent deficit in winter time in a system which has been crumbling for seven months."