WASHINGTON: US-led forces have targeted Islamic State (IS) militants with eight air strikes in Syria and nine in Iraq since early on Friday, the US military said on Saturday.

In Syria, the air strikes hit IS positions near Al Hasakah and Kobani, the Combined Joint Task Force said in a statement.

In Iraq, they hit IS positions near Bayji, Mosul and Fallujah, among other places, it said.

Meanwhile, heavy clashes between fighters and Syrian troops claimed nine lives. Hours after the shelling, helicopter gunships struck a market in Aleppo’s fighter-held neighborhood of Maadi in apparent retaliation, according to the Britain-based Syrian Observatory for Human Rights and the opposition-run Aleppo Media Center.

The Observatory said the airstrike killed nine people and wounded dozens, some seriously. The Aleppo Media Center reported casualties but did not provide a precise toll.

The violence came as the head of the UN agency for Palestinian refugees planned to undertake an “urgent mission” to Damascus later Saturday amid concerns over the situation in the Palestinian refugee camp of Yarmuk, most of which has been captured by the IS. Government warplanes have dropped explosives-filled barrels on fighter-held neighborhoods in Aleppo and other cities, killing thousands.

Aleppo, Syria’s largest city and its former commercial hub, became a key front in the civil war after fighters launched an offensive there in July 2012. Pierre Krahenbuhl, head of the UN agency for Palestinian refugees, known as UNRWA, was meanwhile set to meet with Syrian and UN officials in Damascus about the humanitarian situation in Yarmuk camp, agency spokesman Chris Gunness said.

Gunness said in a statement that there are deepening concerns over the safety of some 18,000 Palestinian and Syrian civilians, including 3,500 children, who remain in the camp.

Gunness later wrote on his Twitter account that UNRWA treated 31 Yarmuk evacuees, including two pregnant women who fled to the nearby neighborhood of Tadamon. He added that the youngest displaced person from the camp is six weeks old. IS militants overran much of Yarmuk last week, establishing a foothold in the Syrian capital for the first time. The incursion is the latest trial for Yarmuk’s residents, who have already suffered through a devastating two-year government siege, starvation and disease.

Residents say there is barely enough food and water, and hospitals have long run out of drugs and supplies.

The Syrian government has said it will launch a military operation in Yarmuk to evict militants, which could cause even more devastation.