Turkey-backed Syrian rebel fighters on an armored personnel carrier (APC) react as they drive to cross into Syrian town of Tal Abyad, in the border town of Akcakale in Sanliurfa province, Turkey, Oct. 18, 2019. Photo: Reuters / Murad Sezer.

Airstrikes on a camp in northwest Syria run by rebel fighters backed by Turkey killed at least 20 people on Monday, a war monitor and a rebel source said.

The rebel source said Russian strikes targeted the Failaq al-Sham faction in their base close to the border with Turkey, killing 20. The UK-based Syrian Observatory for Human Rights put the death toll at 34, with dozens wounded.

Syrian government forces, backed by Russian air power, have driven rebels back to a pocket of territory adjoining Turkey after more than nine years of conflict triggered by protests against President Bashar al-Assad in 2011.

Ankara sent thousands of troops into the region this year to stall the Syrian government advances and prevent an influx of refugees from the Idlib border region into Turkey.

Monday’s airstrikes targeted the camp near Kafr Takharim, about 10 kilometers (6 miles) from the Turkish border in Syria’s Idlib Province, the rebel fighter said.