A Syrian monitor says Islamic State militants have launched an attack on government-held areas of the Syrian city of Deir el-Zour.
The British-based Syrian Observatory for Human Rights reports several explosions rocked the eastern city in the intense offensive.
The monitor reports that more than 30 people have already died in the fighting, including 20 IS jihadists and 12 regime fighters.
Officials say the Syrian government used warplanes to beat back the militants.
Unconfirmed reports say dozens of people have been killed.
The Islamic State group controls most of Deir el-Zour province, but government forces have maintained control of the provincial capital.
The capital has been under siege by IS fighters since 2014, but government forces have been able to hold out because of supplies dropped to them from the air.
According to the monitor, IS jihadists had been preparing for Saturday’s offensive for some time, recently bringing in reinforcements and extra ammunition.