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.

As US-backed forces advanced, 22-year-old Dima Qatran buried one of her twin babies, then picked up the other and fled the Islamic State group's crumbling pocket in eastern Syria.

Military operations against the Islamic State group in Syria are wrapping up and the last pocket of the jihadists' "caliphate" will be flushed out within a month, a top commander said.

Turkey could establish a "security zone" in neighbouring Syria on its own, Foreign Minister Mevlut Cavusoglu said on Thursday, as the United States plans to withdraw troops from the war-torn country.

Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan will hold Syria talks in Moscow on Wednesday, with Turkey saying they will focus on Ankara's so-called "security zone" in northern Syria.

Nearly 5,000 people, including almost 500 Islamic State fighters, have since Monday left the jihadist group's last bastion in eastern Syria, where IS continues to lose ground, a Britain-based monitor said.