It gets dark, and cold, and people are getting hungry.

Israel closed border crossings Friday, not allowing even UN humanitarian aid trucks carrying basic food. Crossings have been closed frequently since October 2007.

"On Wednesday or Thursday we will have to suspend our food distribution programme in Gaza," spokesman for the UN Relief and Works Agency (UNRWA) Christopher Gunness told IPS. "We are running out of fuel for vehicles."

With 80 percent of the 1.5 million people in Gaza dependent on food aid, this latest severing of food sources is building up to a humanitarian catastrophe.

Umm Jamal Al Baba, a 60-year-old from Rafah camp, stands visibly tired in a queue of hundreds for bread. "I can no longer make bread in my house -- there is no gas for cooking, no electricity."

Now that rice had disappeared under the siege, or priced out of the reach of most people, bread means survival for Palestinians in Gaza Strip.

This Palestinian area voted in Hamas, which does not recognise Israel, and this has led to continuing Israeli reprisals. The narrow strip of land has Israel on one side and the Mediterranean on the other, and people are dependent on food and other resources coming in from the Israeli side.

The situation for Palestinians is somewhat better in the West Bank bordering Israel and Jordan. Israel is more accepting of the other Palestinian party Fatah which runs the Palestinian Authority there. The two Palestinian areas are cut off by Israel in the middle. Prosperous Israel next door is a world apart from the world of Umm Jamal.

After a long wait, Umm Jamal leaves with a small bag of bread. "This will not be enough to feed my grandchildren for even one day," she says. "I can only hope this situation does not go on for long, because I don't know how much longer we can last at this rate."

And what if the situation does not improve? That, she said, could be the beginning of a "hunger revolution".

Like others, Umm Jamal woke up Monday to shuttered shops and desolate streets because of the petrol shortage. The main power plant shut down Sunday after Israel blocked fuel supplies, plunging much of the Gaza Strip into darkness. The little electricity supplied has been shared among different cities and camps for a few hours a day.

"Gaza needs 250-260 megawatts of electricity, not counting the needs of factories and workshops, many of which have been demolished and shut down," says Jamal al-Dardasawi, spokesman for Gaza's Palestinian Electricity Company. "Israel and Egypt provide roughly 50 percent of Gaza's electricity needs."

Dardasawi said Israel has destroyed many electricity lines during its latest military invasions, leading to further cuts. "The electricity crisis in Gaza came following the manufactured fuel shortages," he said. "If the shortages continue, they will gravely affect electricity supplies to hospitals and clinics." Medical centres already suffer from lack of medicines, blankets and food.

Gaza City streets and houses are in utter darkness. Forty-one-year-old Ahmed Hussien searches the shops in vain for candles for his children. He leaves empty-handed. "I have been to four shops; there are absolutely no candles available in the market."

Hussein says he cannot see why Israel does not let even candles through. "Will I threaten Israel's security if I light one candle for my kids in a dark night, so they don't cry all night?"

Worldwide, the flame of a candle is seen as a symbol of hope. In Gaza, it is now a basic tool of survival. And too many cannot find it.