When Saada al-Aboud saw Islamic State fighters bringing weaponry into her village near their Syrian bastion of Raqa, she feared she and her family would become human shields for the jihadists.

"Daesh fighters brought heavy weapons to our village and stayed among us so that if there were strikes they would hit us," the 45-year-old told AFP as she fled her village of Al-Heisha, using an Arabic acronym for IS.

"They wouldn't let us leave," she said, her lined face marked with a Bedouin chin tattoo.

"We had to escape by running out into the fields, with our children and old people. What else could we do? We left everything behind."

Al-Heisha, 40 kilometres (25 miles) north of Raqa, was already controlled by IS, but the jihadists began moving artillery there as they came under pressure from a new assault to seize their stronghold.

The US-backed Kurdish-Arab alliance known as the Syrian Democratic Forces (SDF) began its operation to capture Raqa on Saturday night, in an attempt to pressure IS as it faces as assault on its Iraqi bastion Mosul across the border.

So far, the SDF has advanced to within 36 kilometres of Raqa, seizing a handful of villages from IS control.

The dual operations in Iraq and Syria have placed unprecedented pressure on the jihadist group, which faces the prospect of losing its two largest remaining population centres, and with them its claim to a "state".

The fighting has prompted a steady trickle of civilians to flee IS territory, most heading towards Ain Issa, 50 kilometres north of Raqa and a key staging ground for the operation.

- Overstuffed pick-ups -

"We were afraid of the planes, and we were afraid of the IS fighters," said 34-year-old Wazira Al-Jeely from the village of Al-Tuwaila.

"When the strikes started, we took off our burqas and said we're done with you, and we ran away," she said.

The fleeing civilians, dozens of smiling children among them, arrived mostly in overstuffed pick-up trucks.

But others came on motorbikes, and some even walked, driving their sheep and goats ahead of them.

SDF fighters stopped the arrivals several kilometres outside Ain Issa, checking identity cards and belongings in a bid to prevent infiltration by IS forces.

The jihadists have already begun fighting back with their favoured tactic -- suicide car bombs -- making the SDF jumpy about new arrivals.

The civilians waited patiently to be processed, their faces covered in dust from the road, some with suitcases and other belongings wedged in around them in their vehicles.

In one pick-up truck, a girl looked out from above a goat, his head peeking through the rails of the truckbed and his brown ears flopping.

"Thank God we've been freed. The situation was terrible," said Mohamed Mahmoud Ismail, on a motorbike with his son.

"A bundle of bread cost 400 pounds ($0.80) and we were dying of hunger," he said.

"If you cut your beard, they'd make you pay 30,000 pounds as a fine, imprison you and confiscate your ID card -- and not return it until you completed a course in Islamic law."

In another vehicle, Heza Attiyeh took a satisfied drag on a cigarette, which IS has banned in territory under its control.

"Thank God for cigarettes," she said enthusiastically.

"Thank God, we're done with IS and now we have come to safety."

Source: AFP