Fighting between Islamic State (ISIS) and Syrian regime forces over Deir-ez-Zor air base in eastern Syria is still underway as dozens from both warring parties have been killed in the past week.
Pro-ISIS twitter accounts said Saturday that the radical group has been very close to overrunning the air base, President Bashar al-Assad's last remaining foothold in eastern Syria.
According to the Syrian Observatory for Human Rights, 18 regime soldiers and 36 ISIS fighters were killed on Thursday.
ISIS forces earlier captured an artillery battalion Friday near the city's military airport, advancing on the facility’s gates.
Local media activist Saray Ed-Din al-Deiri told Zaman al-Wasl the regime army targeted ISIS fighters with missiles containing toxic gas, with cases of asphyxiation reported by medics from the neighboring city of al-Mayadeen.
After more than four years of civil war, Assad's influence is mostly confined to the cities of western Syria, with the rest of the country largely held by ISIS forces, other insurgent groups or Kurdish militias, which control much of Syria’s north.