A statement released by the group said that all men between the ages of 20 and 30 would be drafted.
"We call on all young Muslim men to head towards our offices as quickly as possible and before the end of a week since we made the call," it read. "Those who do not will be subjecting themselves to questioning and punishment."
ISIS has faced pressure on all sides as it rallies to defend its remaining territories following the fall of Mosul to Iraqi forces last month.
Last week, Syrian government forces said they were nearing the last major town held by ISIS in Homs province, part of their multi-pronged advance towards the group's strongholds in the east of the country.
A military source told AFP that combat operations would accelerate towards the town of al-Sukhna, some 50km from the administrative frontier of Deir Ezzor province, where ISIS has redeployed many militants after losing ground in Syria and Iraq.
"Capturing al-Sukhna means opening the door and path for forces to move to Deir Ezzor directly," the source told Reuters, adding that the military had captured positions 8km southwest of the town on Wednesday evening.
According to the pro-government Al-Masdar News site, forces loyal to President Bashar al-Assad cut off a supply line to the village of Thardeh in the Deir Ezzor southwestern countryside.
Led by the al-Qassem group of the Republican Guard, the Syrian army reportedly managed to capture one square kilometer of territory around the Deir Ezzor cemetery following clashes with ISIS in the west of the province.
Deir Ezzor, which borders Iraq to the east, is still almost entirely under ISIS control. The Syrian government has held on to a pocket of territory in the provincial capital of Deir Ezzor city, and at a nearby air base.
On Friday, the Revolution Commando Army - former a US-backed rebel group named the New Syrian Army - announced it would also be moving on ISIS positions in Deir Ezzor alongside other opposition groups.
In April 2014, ISIS drove out Syrian opposition forces from Deir Ezzor while pro-government troops remained in control of several neighbourhoods and the military airport.
Backed by US-led coalition air strikes, the alliance now reportedly controls more than 50 percent of the city, according to the so-called Syrian Observatory for Human Rights, a Britain-based monitor.
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4 August 2017 - 16:24
News ID: 846158
(AhlulBayt News Agency) - The ISIS has ordered the conscription of all men aged 20 to 30 in the Syrian province of Deir Ezzor, as the militants face the prospect of losing their capital in Raqqa.
Backed by US-led coalition air strikes, the alliance now controls more than 50 percent of the city, according to the Syrian Observatory for Human Rights, a Britain-based monitor.