Once cogs in a dynamic industrial engine that helped power Syria's economy, the factories in a sprawling zone in the heart of battle-ravaged Aleppo now stand largely silent, the workers mostly fled.

In their place, thousands of people sheltering from the violence that has swept Syria's northern commercial capital since July, and from the severe winter weather that has brought misery to much of the Middle East.

The Sheikh Najjar complex opened five years ago in Aleppo, Syria's commercial capital in the north of the country, and was quickly touted as an economic success story.

Today it works at about only 20 percent capacity, according to one estimate.

This is more to do with a lack of electricity and a dearth of supplies of much-needed raw materials than as a result of being directly caught up in the fighting.

In the initial weeks of the conflict last July, regime forces sent artillery shells smashing into the complex, alarming factory owners who begged that they be spared the violence so they could keep the wheels of industry turning.

"Businessmen reached an agreement with the regime so that their plants were not hit," says Rafat, a local rebel spokesman.

"They also demanded that the rebels leave the area in order to avoid clashes" and prevent disruption of the activities of "the largest and the most important industrial complex in Syria".

With the fighting shifting elsewhere by agreement of the warring parties, factory owners began trying to revive their businesses.

Mohammad Olawi, who owns a textile unit in Sheikh Najjar, says he managed to reopen his facility after being forced to keep for months.

"A few weeks ago I reopened. I need money to feed my family," he says, optimistically.

For now his textile plant is operating, as is a biscuit factory that reopened in November.

But the raw materials for the biscuits, sugar from Brazil and flour from Malaysia, simply aren't reaching Aleppo, says Munir al-Hassan, production manager at the plant.

"If this continues, we will have to close down again," he says dismally.

Rebel spokesman Rafat paints a bleak picture of a once well-oiled industrial complex now gradually stuttering to a halt.

"Thousands of workers have lost their jobs because of the war," says Rafat.

"This industrial area was the economic engine of Syria and one of the main sources of income in Aleppo."

Rafat said the rebels fighting President Bashar al-Assad's forces have tried to persuade the factory owners to reopen their units.

But "most of them have fled", he says, while adding that several plants remained closed because "some owners had good relations with the regime and feared retaliation."

With the flight of the workers, came the influx of those displaced by fighting which according to the United Nations has seen more than 60,000 people killed across Syria in the past 22 months.

Today the warehouses and factories are teeming with hundreds of families who fled from Aleppo's daily bloodshed and are sheltering from the grim weather.

Mohammed Kurdi, who hails from the city's Masaken Hanano neighbourhood, is one of the luckier ones, settling with his family in the factory where he used to work.

"I asked the owner for permission to live here and he agreed on condition that I keep a watch" on the plant, he says warming his hands around a fire belching out thick smoke. His two children sit silently beside him, also warming their hands.

Not unexpectedly, small shops have sprouted in almost every corner of the complex, offering everything from vegetables and various foodstuffs to clothing. One enterprising operator has even opened a laundry.

"About 700 families" have taken refuge in the industrial zone since the fighting erupted in Aleppo, says Abu Hussein who lives with his family in a half-built -- or half-destroyed -- factory.

Three families, comprising a total of about 30 people, live in the shelter along with his family.

We have "no light, no water, no heating, nothing," says Abu Hussein.

"We have to burn plastic, wood, anything we find to keep us warm," he says, as his children, unwashed for days, sit beside him.

But then "at least we are safe and sound, away from the war."