Israel agreed under intense international pressure last night to allow a one-off delivery of fuel and medicines to Gaza to avert a humanitarian crisis.

Ehud Barak, the Defence Minister, said that he would allow the emergency shipment after the Gaza Strip's sole remaining power plant shut down for lack of fuel and UN officials gave warning that they would be forced to stop food handouts to about a million Gazans if the total blockade, imposed last week, was not lifted.

President Mubarak of Egypt had called Mr Barak and Ehud Olmert, the Prime Minister of Israel, to urge them to end the blockade. Israel had hoped that it would force Gaza's Islamist rulers to end the constant rocket attacks on Israeli towns close to the Palestinian territory.

The announcement came as Gazans queued for hours for basics such as bread and petrol, and health officials said that hundreds of hospital patients could die soon. Israel accused Gaza's leaders of turning off the power themselves to manufacture a crisis, a charge denied strenuously by Palestinian electricity officials.

“It is staged by Hamas, it's only a ploy, it's a fabrication,” said Arieh Mekel, an Israeli Foreign Ministry spokesman. Israel had cut off diesel supplies to Gaza several days ago, forcing the power station to close, he said, but it was still providing enough power to the area to avoid a crisis.

Kana Obeid, deputy head of the Gaza power authority, said that the closure of the power plant, which provides 30 per cent of Gaza's electricity, had led to an overload of the run-down grid - which was already falling apart because of previous closures and longstanding restrictions on importing spare parts. Mr Obeid noted that at least one electrician had been killed by electric shock while trying to keep the system running and several others had suffered severe injuries.

Hundreds of people were queueing for hours outside bakeries yesterday as shops shut down for want of electricity. Men could be seen in some areas chopping wood for fuel in the cold weather, while mothers dressed children in multiple layers of clothes to keep them warm.

Khalid Radi, a spokesman for the Hamas-run health ministry, said that hospitals were short of drugs and fuel and were running on generators that would sputter out if more fuel were not shipped in soon. “The lives of about 1,700 patients are under serious threat,” he said. “We have already lost 77 patients because they couldn't seek serious treatment outside Gaza because of the siege.”

The UN Relief and Works Agency, which helps the refugee populations of Gaza, said that it was close to being forced to end its food ration handouts. A spokesman said: “Because of a shortage of nylon for plastic bags [for sugar and lentil rations] and fuel for vehicles and generators, on Wednesday or Thursday we are going to have to suspend our food distribution programme to 860,000 people in Gaza if the present situation continues.”

Another UN agency supporting a further 270,000 Gazans said that it had supplies to last only until the end of the week.

As the blockade of Gaza has taken hold, the number of rocket and mortar-bomb attacks has dropped dramatically. “As far as I'm concerned, all the residents of Gaza can walk and have no fuel for their cars because they have a murderous terrorist regime that doesn't allow people in the south of Israel to live in peace,” said Mr Olmert, before the one-off shipment was given the green light.

“We won't let there be a humanitarian crisis in Gaza but we definitely won't let the life of Gaza residents be pleasant and comfortable.”