Kurdish-led forces said Saturday they were holding up the announcement of final victory over the Islamic State group for "a few days" because the large number of civilians remaining on the battlefield had forced a delay.

U.S.-backed Syrian forces were clearing two villages in eastern Syria on Thursday of remaining Islamic State militants who are hiding among the local population, and detaining others attempting to flee with the civilians, the U.S.-led coalition said.

The coalition said the clearance operations were taking place in the villages of Shajalah and Baghouz, near the border with Iraq.

The cry echoed across the chalk-dry Syrian plain: "Water!" Within seconds, the truck carrying a few dozen bottles was emptied by parched refugees who had spent the night out in the open.

At least 300 women and children, mostly Iraqi, had slept amid the desert scrubs after escaping the Islamic State group's final redoubt of Baghouz in eastern Syria.

U.S.-backed forces pressed the battle to expel diehard jihadists from the last pocket of land under their control in eastern Syria on Tuesday after hundreds fled the holdout overnight.

Umra Abbas Ammour, 60, dreamt of safety as she and her family fled jihadists in eastern Syria, but hours after reaching US-backed forces her son, daughter and granddaughter were all dead.

Turkish President Recep Tayyip Erdogan on Sunday said his government maintained "low-level" contact through its spy agency with the Syrian regime despite being one of its most fervent critics.

Four children were among at least 11 people killed when a war-damaged block of flats collapsed in Syria's second city Aleppo on Saturday, state media said.

One child was pulled out alive from the rubble of the five-storey block after rescue teams toiled, many of them with their bare hands, to remove the shattered breeze blocks that had buried him, AFP photographers reported.

Syria and Iran signed 11 agreements and memoranda of understanding late Monday, including a "long-term strategic economic cooperation" deal aimed at strengthening cooperation between Damascus and one of its key allies in the civil war that has torn the country apart.

Syria's "natural place" is within the Arab League, Tunisia's foreign minister said Saturday, ahead of the organisation's annual summit in Tunis in March.

Coalition missile strikes have killed 42 people including 13 civilians in what remains of the Islamic State group's last holdout in eastern Syria, a war monitor said.