Islamic State kills 20 as it storms Assad stronghold in Syria's Deir Ezzor

Islamic State (IS) fighters on Saturday seized control of the al-Assad Hospital in Syria's divided eastern city of Deir Ezzor, marking a significant advance.

Activists on the ground suggested communication networks in the city went down as IS advanced, reportedly detonating a car bomb at a checkpoint manned by pro-government soldiers in the eastern district of Hay al-Muwazzafeen.

As battles continued into Saturday afternoon, IS announced a "military zone" around a base in the east of the city and warned civilians against approaching.

During their advance, the militants reportedly seized control of 20 civilian homes in countryside east of Deir Ezzor, whose owners were working outside Syria, either in the Gulf or in agriculture in Turkey.

Photos shared by activists showed front doors spray-painted with the phrase "Islamic State real estate" in Arabic, after the militants expelled people from the properties.

A Saturday-morning assault on the al-Assad teaching hospital by IS fighters killed 20 pro-government soldiers, according to British-based monitor the Syrian Observatory for Human Rights, while opposition news site Deir Ezzor 24 said 10 IS fighters were killed.

Displaced families had been sheltering in the hospital, the local correspondent of Syrian news site Ennabaladi reported, saying that a number of civilians had also been killed.

The attack left IS in control of the hospital, which lies at the eastern entrance of the city, as well as a university accommodation block nearby, according to Sky News Arabia.

Radio Sham, a domestic Syrian station, reported IS had taken several doctors and other medical staff hostage, although it has not yet been possible to verify this.

Shortly after the hospital's capture, opposition activists said forces loyal to the government of President Bashar al-Assad launched a wave of arrests targeting young men in government-held areas of the city.

Activists have previously reported mass arbitrary arrests in Deir Ezzor aimed at conscripting young men into government armed forces.

Deir Ezzor has been divided for years, most recently with pro-government forces, rebels and IS all fighting it out to rule the city.

The situation has had a devastating effect on the city's civilians, many of whom have been prevented from leaving by the forces in control of their areas.

A local woman, who called herself Samira, told Deir Ezzor 24 earlier this week that she wakes up at 3am to take her place in a queue that can last up to six hours for bread.

She spoke of "crazy" prices for staple foods in the town, where a kilo of cooking fat can cost $55, saying that she is usually forced to feed her children just bread and water for breakfast.