ISIL Takfiri group militants seized around 2,000 civilians to use as "human shields" Friday as they fled their stronghold of Manbij in northern Syria, US-backed forces and a monitor said.

ISIL Takfiri group militants seized around 2,000 civilians to use as "human shields" Friday as they fled their stronghold of Manbij in northern Syria, US-backed forces and a monitor said.

The Arab-Kurdish alliance known as the Syrian Democratic Forces (SDF) expelled most of the ISIL terrorists from Manbij last week, but dozens continued to put up tough resistance.

On Friday they withdrew from a northern neighborhood heading for the ISIL-held town of Jarabulus along the border with Turkey, taking the captives with them.

"While withdrawing from a district of Manbij, Daesh (ISIL) militants abducted around 2,000 civilians from Al-Sirb neighborhood," said Sherfan Darwish, spokesman for the Manbij Military Council, a key component of the SDF.

"They used these civilians as human shields as they withdrew to Jarabulus, thus preventing us from targeting them," he said, adding that women and children were among those taken.

The Britain-based Observatory, which relies on sources inside Syria to cover the war, gave a similar report, saying ISIL forced around 2,000 civilians into cars it confiscated.

The Takfiris, who have suffered a string of losses in Syria and Iraq, have often staged mass kidnappings when they come under pressure to relinquish territory they hold.

In January, IS abducted more than 400 civilians, including women and children, as it overran parts of Deir Ezzor province in eastern Syria. It later released around 270 of them.

The EU denounced the use of civilians as human shields, saying in a statement that "Daesh (ISIL) continues to pose a threat to the people of Syria, Iraq, the region as well as to Europe and beyond".

ISIL has also used civilians as human shields, booby-trapped cars and carried out suicide bombings to slow advances by their opponents.

Thousands of civilians were held captive by the group in Fallujah which Iraqi forces recaptured in June after a four-week offensive.

On Friday, the SITE intelligence Group said IS had killed five men in Iraq for smuggling people out of territory it controls.

SDF forces captured Manbij on August 6 but continued to battle pockets of Takfiris in parts of the town.