Islamic State has attacked a hospital in Deir al-Zor and seized territory on the edge of the besieged eastern Syrian city still partly controlled by the government, the militant group says.
Islamic State's Amaq news agency said its fighters stormed the Assad Hospital on Saturday and also took control of a check point, a fire station and university accommodation in the city close to Syria's eastern border with Iraq.
The agency also said the militants had taken territory near the al-Tayyam oil fields, in the vicinity of the state-held military airport on the city's southern edge.
Islamic State controls most of Deir al-Zor province and has laid siege since March last year to the remaining government-held areas in the city of the same name.
Deir al-Zor province links Islamic State's de facto capital in the Syrian city of Raqqa with territory controlled by the militant group in neighbouring Iraq.
The Syrian Observatory for Human Rights said there were reports Islamic State had detained medical staff and taken some government soldiers prisoner in Deir al-Zor.
It said there were ongoing fierce clashes between government forces and Islamic State in the area after the militants attacked the southwestern edge of the city at dawn.
The fighting killed at least 20 members of the Syrian government forces and at least six Islamic State fighters, the Observatory said.
Islamic State said it killed 25 government troops and took three prisoner.
Russia's RIA state news agency on Saturday reported a source within the airbase on the southern edge of the city as saying an Islamic State attack had been repelled.
The Syrian government and its Russian allies make regular aid drops into the encircled city and there are frequent air strikes on Islamic State targets in and around Deir al-Zor.